It looked pretty bad. He was hobbled significantly. It was immediately obvious he wouldn't be playing in game 6 and I think its definitely up in the air if he can go in game 7 at the earliest.
Game 6 is less of a big deal, because they were unlikely to win that one anyway but Game 7 is the rough one. Houston's offense getting even more one dimensional in a game 7 is scary and Harden has struggled when its clear he is the only one to focus on in the offense.