If so, what part of your name was it (like first or last) and did it effect you in any negative way as far as employment and such?
Yes, to simplify my firstname.
No negative effects. It makes paperwork easier. It makes dealing with foreigners easier. My passport and my driver’s license now print identical versions of my firstname, which makes renting cars in non-Romance-countries easier.
I considered simplifying my first lastname as well (it’s three words), but fuck that shit. That lastname is like an idiot cousin: it’s an imbecile but it’s been in the family for a long time and we’re fond of it. And most of the pain I get regarding lastnames isn’t even linked to that one lastname, but to whether to use one or two and how exactly to do so; it really wasn’t much of a gain.
Technically, I was born with a hyphenated name. I apparently hated the attention it gave so it got changed to my dad’s name. The practice can be a little bit “precious.” I don’t remember any of this, I was pretty young. When filling out forms and background checks etc., I don’t fill in the “have you had other names before?” section. Never had a problem.
Nava: 3 words meaning both your parent’s names (+ something else?) as is common in Spanish speaking countries? Or are they inseparable parts (maybe “de la” etc.)? You can be as vague as you want.
Kind of.
When I was young my family and friends always called me by my middle name which is pretty unheard of outside my ethnicity. I didn’t mind all through out school but once I got out of college and got a real job it just became a pain in the ass so I started going by my first name which is much more common.
I didn’t officially change my name, but I sort of did. I’ll explain.
Emily is the name I go by, but it’s my middle name. Same thing with my sister and her name. When my parents registered us for school, they did so under our full names, which had the unintended effect of having teachers initially thinking that we went by our first names. My sister and I didn’t like this. I mean, the teachers did find out that we went by our middle names, but this first-name thing happened in every class, and my sister and I found it tiresome.
When I registered for university, I registered under only my middle name and last name.
It saddens me to hear that there are non-Romance-countries. 
Because the OP asks for consequences, I understand his question to be about taking official or legal steps to have one’s name changed, not just deciding to use a different name on a social level or, for example, emphasizing one’s second name instead of one’s first name. Is that right?
Indeed. Those people are strictly business.
It’s common in Thailand to change one’s name on the advice of an astrologer or fortune teller. There have even been high-profile murder cases where the perp credited the name change with resulting in his innocence being proven. (The tons of cash the perp’s rich father dropped on officials had nothing to do with it, of course.)
My wife’s parents, while keeping their own Chinese surnames, changed all their children’s surnames to something more Thai. My wife was only a couple months old when that happened but that had to be documented when she was applying for her Immigrant Visa here in the US.
Didn’t I say first lastname? checks Yes I did.
Three words, one lastname. The one that I use when speaking with foreigners, except when they insist in referring to my lastnameS as my lastname. With the second lastname, makes four total words.
It’s in the form “Commonlastname from Place”, which is relatively frequent in northern-central Spain (mainly Navarre, Vizcaya, Álava, Guipúzcoa, Rioja, Burgos) but unusual otherwise. No dashes, as dashes are a 19th century novelty and the idiot lastname is older than that.
Here’s a thread from two months ago on almost the same topic: http://boards.straightdope.com/sdmb/showthread.php?t=831882
Bottom line: It’s a total non-event.
Sort of. My father started using a different family name around when I was born, but used the original name on my birth certificate. But from school registration on, I never had any occasion to use the original name. Passport was issued under new name (affidavit required) and eventually the commonwealth even issued a birth certificate under newname. So I cannot say I changed it really.
Yes, first & middle name were changed (John Dewey to Jason Daniel).
Some minor problems with the IRS, not recognizing the change for 4 years.
I had to change my middle name twice for my military records. I thought that it was Steven so that’s what was on my enlistment papers. Later on I got married and saw Stephan on my Catholic baptism records so I changed it to that. Then I applied for a passport and saw that my actual birth certificate did say “Steven”.
Now when asked for my middle name, I just say S.
Hey, my middle name IS “S”! With no period, just like Harry S Truman. My parents sort of wanted to give me my mother’s maiden name as a middle name, except that she always hated it because no one could spell or pronounce it. So they settled on just the initial. Why they didn’t put a period on it, I have no idea.
I’ve been waiting all my life for some bureaucrat to object (“hey, you were supposed to put your full middle name, not just your initial”) so I can set them straight, but in over half a century, it has never once been a problem.
Try not having a middle name at all.
I have had people insist that I MUST have a middle name, they won’t let the baby leave the hospital without one! Nope, not true.
I have no middle name and a hyphen in the surname. While I occasionally have had issues with computer systems I find human beings with odd notion of what MUST happen, or what they THINK is the law, to be far more troublesome.
My middle name is Stephen. A few years ago I was traveling for work and on my way home, TSA noticed my boarding pass had “Steven”, while my drivers license had “Stephen”.
I hadn’t noticed. My ticket had been purchased by my business manager (who also does much of my tax stuff, so she should have gotten it right).
When, out of frustration, I asked the TSA guy if it was really that big of a deal, he turned it up a notch. It seemed like he was proud he caught the minor discrepancy and was getting off on making me squirm.
Security Theater. Curtain time, now.
Yes, well kind of. I was born with two middle names, Anthony and Patrick. In about the 2nd or 3rd grade, I’d use just Anthony because I realized everyone else had one middle name. And then some time later I realized my initials spelled RAT, which of course I didn’t like. So I dropped Anthony and only used Patrick from that point onward.
Patrick is on my drivers license, my passport, my marriage license, my Social Security and bank accounts, my military records… It’s on everything.
And Anthony Patrick is still on my birth certificate and baptism certificate.
What ethnicity is that? It’s not nearly as unheard of as you are imagining. I’ve known several people who go by their middle name, all of whom are standard Caucasian.
A friend of mine in college went from the regular first middle last to a single unusual name. She had it legally changed with no issues. When she went to change her name at the university, the computer had to have a first name and a last name as a minimum. For people like her, they used her single name as the last name and “NFN” (no first name) in the first name slot.
My grandfather had a long ass middle name and he hated it. So my dad and uncle have no middle names. I don’t have one. None of my siblings have one. None of my cousins have one. I’ve never had much trouble and I’ve never heard any complaints from any of the others.
My dad is another “kind of” case - when his family came to the states, a letter was added to his last name. Fifty years later, when my dad was born, his father decided to go old country and removed the extra letter. Ditto my dad’s younger brother. However, they always went by the letter added name. It wasn’t until my dad applied for a Social Security card that he discovered the change. He was going to legally change it, but Social Security told him don’t bother - he had gone by the letter added name for so long, it kind of absorbed.