Just completed two nights here.
Good news for those who pick hotels primarily because they offer breakfast, the Ren Chelsea is now offering elite breakfast. The FD provides the standard Marriott "Continental Breakfast" coupon for elite+1, but the actual breakfast is basically your standard low end lounge fare (steam trays of sausage, bacon, and eggs; plastic shelves of breads; yogurts; etc).
The buffet is in the room next to the elevators that looks like it was supposed to be the lounge, but there's no seating there. Instead, you enter through the restaurant (which is now full service) and walk back to a special seating area that looks like it was supposed to be outdoors, but was covered by a tin roof. There are three large picnic tables that seat about 8 people each, and two smaller tables. There's also a heated area that was roped off. The area was leaking from heavy rain. (Apparently under some circumstances they'll move the elite breakfast to the 2nd floor ballroom, maybe when it gets busy.)
The rooftop nightclub has apparently (re)opened, and in particular on weekend nights can be pretty loud until about 4am. The FD agent proactively offered to place us on lower floors, and we ended up on 15F and 20F. From 20F, I was able to barely make out the nightclub when the room TV and HVAC were off, but basically any noise covered it up. If you're staying on a weekend night, I'd definitely recommend a lower floor.
When the nightclub is open, it also takes one elevator out of service. The other three were mostly sufficient (maybe because the hotel wasn't completely full), but the hotel could benefit from the hallway dispatch system that the Ren Midtown and Marquis use.
The hotel appears to be transitioning from Aveda to EcoWell, or maybe they ran out of Aveda and had to supplement? (My room had a mix.) I'll have to go dig up the toiletries thread and ask there. Still no pen/paper in the room, unlike the Ren Midtown.
The FD no longer appears to be waiving the $25 "destination fee". That said, I price my stays by comparing a/i pricing, and the total Ren Chelsea price was in line with other hotels I was looking at, so as far as I'm concerned that's between the hotel and the taxing authority they're cheating revenue from.
For anyone considering both the Ren Chelsea and the Ren Midtown, at the moment Chelsea seems to be more popular on weekends and Midtown seems to be more popular on weekdays.