I just did the install and found it to be extremely easy. I'd previously polished the gun, so it was just dropping in parts. The only hurdles I had were getting the firing pin roll pin out, and... I guess the new one in. I've heard some people need the disconnector fitted, but mine dropped in without a hitch.
It's fine and definitely better than before, but maybe because I'm coming from an already polished P01 I wasn't too blown out of the water with it. The reset and trigger pull are nicer but it still has quirks that bug me. I don't think I messed anything up, but I have no point of reference on how it should feel. Maybe I'm just being picky because of how over the top everyone's adoration for the kit is.
That being said, I'd still vote for doing the upgrade if you have the money to spare. I like it more than stock, I just don't OH MY GOD FREAKING LOVE it more.