I wish I would have stayed just playing hardcore characters instead of pushing into inferno with my favorite one so I could see what all the fuss was about before it got nerfed. There are two big factors that made me stop playing it after two months. One, you cap while you're still finishing hell difficulty and the only way to progress your character(s) is through gear so you spend a lot of time doing something not very rewarding and doesn't feel like you're making any progress either. Two, putting all the annoying AI mobs in the same act just makes me not want to take any of my characters through Act 2 again, hardcore or not. I get very tired of having so many mobs that have some part of the AI where you can't hurt them, ie underground, flying to an area inaccessible to players, turning invisible. It's definitely worth picking up in a bargain bin eventually, but it's not worth shelling out the $60 for it especially if you have to upgrade the computer to run it too.
Edit: Minor note for the one I listed as the first one that bugged me. I didn't farm in either D1 or D2 because I don't enjoy farming. I didn't enjoy farming in WoW either and would generally only do so if a guildie mentioned something specific they were trying to get but didn't have time or whatever. If you did farm in D1 and D2, you'll probably be fine with farming inferno. I just know I wasn't.
Edit: Minor note for the one I listed as the first one that bugged me. I didn't farm in either D1 or D2 because I don't enjoy farming. I didn't enjoy farming in WoW either and would generally only do so if a guildie mentioned something specific they were trying to get but didn't have time or whatever. If you did farm in D1 and D2, you'll probably be fine with farming inferno. I just know I wasn't.
Intolerant monkey.