It’s an easy job.
Unless.
Unless your under sink shut off valves are corroded or encrusted, and won’t close.
And then you find the main house valve is in the same shape.
So you have to shut it off at the street, but you don’t have the right tool. And it’s under a pile of dirt. And the valve is stuck. Better go buy the right tool, so you don’t break the main. That would be bad!
So first you replace the whole house valve, which you have to solder. You do have a MAPP torch? Hope you’re good at it. Might take two tries if you’re not. Don’t melt the teflon seals in the meantime. If so, another trip to HD.
Then you replace the under sink valves. Probably soldered, so they have to be cut off. Too tight in there to use the hacksaw. Got a Dremel? A pipe cutter? hope so. uh oh, they didn’t leave you enough room. Or enough pipe coming out of the wall. Now you have to solder right next to the wall. Don’t set it on fire! Did you get the right adapters? Another trip to HD!
By now you need to find the 24 hour home depot, because you can’t leave it undone, because you have the water turned off. No shower, no toilet. Fortunately, there is one. Unfortunately, it is across town. Hope they have the part!
Back home, put the valves in. Now to remove the faucet. Oops, corroded. Nuts frozen. Can’t move them. Must cut. No room! An hour fighting the retaining nuts, which includes the use of hammers and chisels and appropriate profanities. Finally, success!
Then it goes together pretty fast after that. Tomorrow, another trip to return the stuff you didn’t need.
And I’d still rather do it myself than pay a plumber. 15 years since the replacement, and not a problem. Plus now I have my own MAPP torch.
Also, if you must replace the shut off valves, use ball valves. They are more expensive, but they don’t corrode shut.