The show stars Adam Scott, who played "The One They Call" Derek in the hilarious 2008 movie Step Brothers, Lizzy Caplan of Tru Blood and The Class and Ken Marino who was on the best web series of 2008 Children's Hospital. Jane Lynch, who has a recurring role on Two and a Half Men and was recently seen in Role Models, Martin Starr of Freaks and Geeks, and Ryan Hansen of Veronica Mars also star.
Scott and Caplan are really the only reason to watch the show. There's a bit of relationship foreshadowing there, for those that are into that kind of stuff, but it looks like they'll be friends for at least the majority of the first season. Adam Scott is not as insanely awesome as he was in Step Brothers, but he's still really funny playing a sarcastic, broken-down man. He does not have the charisma necessary to carry a show, but for those that like his kind of humor you're in for a treat. As for Caplan, she's probably the best actress on the show, and is both witty and a good character that you want to root for. Rob Thomas excels at writing for females, and with him behind the show that's probably the reason I enjoy her character Casey Klein so much.
If you like Seasons 4-5 of Michael Scott on The Office then you will like Ken Marino's character Ronald Donald. He's as goofy and as unqualified to be a leader as Scott, but his jokes mostly fall flat in my opinion.
Enrico Colantoni (Veronica Mars, Just Shoot Me and currently Flashpoint) makes a guest appearance and while his comedy isn't for everybody, if you enjoyed him on any of those shows you'll like his spot here.
The show suffers because of the other three stars. I enjoy Lynch on Two and a Half Men but here she just plays an irritating drunk. Think Nina Van Horn from Just Shoot Me, but not nearly as funny. Hansen and Starr are just so plain and bland, but hopefully they'll develop more in the future.
Another problem is that this show is really a drama wrapped in a comedy package. The pacing is unclear as to whether you should be laughing or feeling for these people, and the transition is not as smooth between the two genres as it is on Desperate Housewives.
Party Down is the kind of show that I feel has potential to get really good in a few episodes, but this pilot will not be turning too many heads.