I'm averaging the dayclub (3 stars) and nightclub (5) stars.
Nightclub: I still think Marquee is an awesome club. I love the fact that they have multiple rooms with different music, and I also love the outdoor pool area. It's like a mix of the best of XS and Tao. Cons are still the same: hip-hop room is too crowded & too many stairs. Lately, they've been hosting a lot of big house DJs, which is fine - though it does push up prices for the fellas. If I were to get table service, I would probably do it either in the hip-hop room (for the music), or outside in the cabanas (for the view of the strip - wow!).
My main gripe about the nightclub is line security - not always very polite. Also, I wouldn't try to go to Marquee unless I were in a group of ALL girls or I had table service. Because Marquee is so popular right now, the mixed group line is utterly ridiculous & the club is not SO amazing that it's worth waiting over half an hour for. Plus you can't drink in line - not even drinks from the Cosmopolitan! Marquee is pretty great, but there are other great clubs in Vegas too. If you get there late and have to wait in the general admission / guest list line (even with comp passes) and if you can see the big shoe statues...dude, just save yourself the trouble and try a different club.
My recommendation is either:
1) Go with a group of all girls and enter from the "all-girls line" (upstairs)... or try to talk your way in with a host, whichever works
2) Book a table or cabana
3) If you must go with a mixed group, get there no later than 10pm. Real talk.
Dayclub: Not worth it unless you have a cabana. They usually have house DJs, so the music is OK for the most part. The pool is decently sized, but it's too crowded to enjoy unless you have your own place to sit. Also watch out for your stuff; my friend's wallet got lifted at the dayclub & the staff were pretty useless in helping us find it.