I just started playing at wpex two days ago, and here are some details of what I've found so far...
Most importantly, the rake: Yes, it seems we do get 100% of it back. In the cashier window there is an account button showing the normal balance, and a rake button showing how much you've earned so far in rake (this gets updated every time you get up from a table). I started playing on Monday, which was the day where everyone got paid their rake. A lot of players were totally elated as they typed away in the card rooms.
As for my own rake so far, this is the end of my third day of playing, and I've accumulated over $120 in rake so far. This is from playing 3 tables at a time, which is the max they allow right now for multi-tabling (I actually sent them an email asking for the ability to have at least 6 tables being played at a time). I've also played over 10 hours each day, mostly at $25NLH, $10NLH, and $50PLO/8 (I had to start my own plo game, but people show up and the table fills eventually).
Software: Over all, it's been fine. There are times though where there is a slightly delayed response to betting/checking/folding. On rare occassion there is also an annoying "socket error" message that keeps popping up, but this goes away eventually.
Players: I've logged enough table-hours on wpex now to safely say these guys aren't tight at all, at least at the lower limits. Perhaps some of them go with the theory "the more hands I see, the more rake I'll get" (which is true). I've especially enjoyed the PLO/8 games where people sit down and really don't have a grasp on the game at all. PLO/8 is my game of choice, but for the whole rake thing I decided I needed to get better at holdem since that's where all the action is right now. So for now I'm just buying in half-stacks at 25 or 10 NLH, and things are going fine. I've seen these guys make a lot of crazy plays so far.
How is wpex making their money then, if they don't collect rake?:
1. Drawing poker players in hopes that they will also make sports bets or play blackjack
2. The money that we deposit in the first place goes somewhere. That somewhere ends up in some sort of bank where they can collect interest, and interest = profit.
Why don't they just eliminate rake all-together?: Strange, but I actually prefer it this way. I like seeing all the money come in that I've been missing out on at places like Party. It's really more interesting this way, and I don't think I'm the only one that thinks this. I'm sure that's what wpex is thinking too.
Hope this clears up some concerns. I had my reservations about this site too for a while, but took the plunge. I'm quite happy with it so far though.