I have put in about 22 hours so far, but I'm very busy right now. I really enjoy playing the game and the campaign is very good. I didn't max out any hero because of said "lategame" absence. It just seems they had a really big brain fart concerning endgame structure.
If you care about maxing all 4 heroes you are looking at about 60 hours playtime which is more than anough for me personally and I find myself going back every once in a while. But you need to be aware that this game is no "mmo" where you can keep playing for months and months.
Also, the way online play and voice chat is integrated is really really good. I hope other developers take notes concerning own projects.
I would still recommend the game for people who are lootwhores like me. Also, Shark Pirates.
Ongoing bet with think-man: He wins if MH4 releases in any shape or form on PSV in 2013, I win if it doesn't.
