A 9mm USP Compact was my first gun. I've put several thousand rounds through it and a few other HK guns. At first I thought it was great, then realized it was just pretty good.
-The normal (non-match) triggers are just ok
-The checkering on the frontstrap goes too close to the trigger guard, and a proper grip causes some discomfort due to the 90ish degree angle on the mag release lever.
-I actually prefer the HK mag release slightly. No grip shifting required. However I wish the release lever were bigger and more contoured.
-It's a little heaver than I think it should be for its size. Compare it to a G19 for instance.
-It's wide, but so are all other double stack guns.
-It's ******* expensive.
-The cost of magazines is absurd.
-It has a proprietary rail system.
-It's extraordinarily reliable, and very durable.
-It's very simple to disassemble and clean.
-It can be carried in condition one, which is good because the double action pull is a little too heavy and far too long.
-It looks good.
I don't think I'll buy another HK, but I sure wouldn't trade one for a Glock either. I was considering another HK as my next gun, but I'll be going with a Sig instead. They screwed up in a few ways, but mostly by not putting a match trigger in the "USP 9 Tactical" and not offering 20+ rd mags for it. Yes I know about the jetfunnel.
The P30 has the most comfortable grip I've ever felt.