I'm not a big fan of the first three Genesis albums, but of those three, Trespass is easily my favorite.
To these ears, "Stagnation" is by far the best track and probably ranks in my top 5 Genesis songs of all-time. There are lots of great bits in there but what I really love is the ending. "White Mountain" is my second-favorite - not a Genesis classic in my book but a very good song all the same. Terrific atmosphere and I don't mind the lyrics.
After that the album drops off for me, though I actually do have a minor soft spot for "Visions of Angels". The beginning of "The Knife" works really well also, but I agree that the song goes on way too long. The whole thing should have been 4-5 minutes with the middle section trimmed severely. Oh, and I find "Looking for Someone" to be really, really annoying.
Still, not a bad album at all. I'll take it over the more popular Nursery Cryme any day.