It saves all your golden cookie clicks across soft resets, so I’d say go for it. The prestige bonus makes a huge difference.
It also saves the achievements you already have on a soft reset. So your kittens will be much more effective the second (and subsequent) times through. And if you’ve gotten far enough to get 93 upgrades, then you’re probably looking at a few dozen heavenly chips from that (each one gives a 2% boost, and the heavenly boost stacks multiplicatively with the upgrade boosts). It will almost certainly be quicker to get those last few upgrades by resetting than by sticking with it.
What does a reset take away?
A little bit of your soul.
I believe it also takes away all of your cookies and everything you’ve purchased (buildings, cursors, and grandmas), but not your Achievements.
And all the cookies you’ve ever bakes are converted into ‘Heavenly Chips’, and give you an increase to your CpS, making it that much easier to advance the next time.
I left the game on for two days and i’m at 577,000,000,000 cookies now.
I reset yesterday, or 14 hours ago according to CCer. I got 49 Heavenly Chips and I’m up to about 400 million cps. Not fast enough! 
Clicking on the ad(s) do not get you any achievements. However, it does get you out of the game as they don’t open in a new window.
How you improve your farm. I’m only making 2000 perminute yet my grandma are making 200,000 per minute.
You don’t. Farms are crappy.
It’s still reasonable to buy them late in the game, just because of the bonus they (and everything else) give to your cursors. According to cookiemonster, I’ve bought my buildings in the optimum proportion, and I currently have 156 cursors, 166 grandmas, 118 farms, 106 factories, 98 mines, 90 shipments, 83 alchemy, 93 portals, 73 time machines, and 64 antimatters (that’s with all of the building-specific upgrades bought).
I’m using Cookie Monster as well. Good info. I like it when computers do what they’re supposed to do - boring tedious stuff while I sit back in charge.
I’ve got…
142 cursers producing 1.2 million
125 grandmas producing 3.3 million
108 farms producing 2,160 thousand… I don’t understand what I did wrong here.
100 factories producing 11,200 thousand
89 mines producing 35,600 thousand
81 shipments producing 89,000 thousand
72 alchemy producing 288,000 thopusand
61 portals producing 4.0 million
41 time machines producing 17.8 million
26 antimatters producing 57.1 million
There was once a time in my life when having baked over 500 trillion cookies would have seemed unlikely.
That time was two days ago.
The heck is wrong with you people.
I got bored with it, so I used a cheat to get infinite money.
[SPOILER]There’s no end to the game, or at least no particularly big developments. The cookies in the Store just stop appearing, and getting 300+ of any building doesn’t upgrade anything.
Sorry.[/SPOILER]
Well, having cheated my way to producing more cookies than the universe has electrons, I guess I’m done.
No vacancies!
What if cookie clicker was one of these “gotchas!” to test humanity’s resolve to stop baking cookies in the face of things like:
Killing 73% of our teenage population.
Killing hundreds of miners in cookie-mining related accidents.
Selling our own grandmothers to optimize cookie production.
Ignoring the strikes of workers in our cookie factories.
Selling our grandmother’s souls and bodies in a never ending lust for ever more cookies, resulting in a truly horrifying situation where they have all become physical monsters and changing the landscape of our planet into a pulsating fleshy mass.
And we all did it. And we all did it several times, restarting the game, knowing what would happen, again and again.
And when that wasn’t enough, we cheated in more cookies.
Cookie clicker proves humanity is beyond redemption. May God have mercy on our souls.
“You could have stopped it.” -Grandma
I <3 drew.