My aunt/uncle stayed at Hotel 91 a few months ago and it was fine. It's not even remotely in the league of the Cooper Square or Standard or even tHoR, but it's an acceptable place to stay if you want to be in REAL Chinatown, probably closer to the Hotel East Houston (or East Houston Hotel, depending on which sign you're reading) minus the roofdeck. Just make sure you get a room on the side NOT facing the Manhattan Bridge, otherwise I imagine the subway noise can be pretty bad.