Reasons I hate Sense:
1) Slower updates, and compared to a Nexus handset, they'll stop coming after a year and a half
2) The dock (in pre-ICS versions) sucked... hard to tap to open app drawer, and no quick browser button
3) The inability (in pre-ICS versions) to change the grid size; 4x4 is unacceptable on a phone like the EVO
4) So many features drained battery that took forever to turn off
5) It handled your contacts different from standard, so if you link contact x and y, you'd only have those linked on HTC handsets going forward... move to Samsung and you start over
6) I hate the colorful look; I prefer to theme my handset with a primary color and then keep the rest black/grey/white. I can't stand the rainbow coloring of Sense
7) No widgets in the notification bar, though in fairness that was TW-only before ICS, and I hate TW too
8) It's been awhile, but I recall the Twitter and Facebook integrations being hijacked from normal... so there was some Footprints app that you had to keep installed taking up space and battery life.
9) Battery life sucked
And for those of you that would say to just change my launcher, in any pre-One X handset, that meant horrible performance because without rooting you couldn't remove the default HTC launcher.