In my experience with the service -- on both coasts and three major US cities -- it was quick, responsive, and relatively free of bugs (though I did encounter a couple). And demos are available for almost every game, so I put at least a bit of time in with nearly every title currently playable. Dirt 2 with DirectX 11 running on my 10-month-old (Apple!) laptop? Speeds along without a hitch. Unreal Tournament 3? No issues (well, other than not finding anyone to play against outside of bots). I was also able to hook up a wired Xbox 360 controller without any additional installation and it worked flawlessly -- the Xbox guide button even brought up the OnLive guide and auto-paused games (madness!). And though I probably wouldn't suggest OnLIve for hardcore, twitch gamers -- and neither would the company itself -- I would absolutely recommend it to everyone else.
That said, there are -- of course -- some downsides. First things first, the list of games available for purchase is ... underwhelming, to say the least. 21 games in total (from AaaaaAAaaaAAAaaAAAAaAAAAA!!! -- A Reckless Disregard for Gravity to World of Goo), without much in the realm of hot new titles, and only a handful of those have been added since the service's launch back in mid June.
Jumping from game to game with the service is eerily fast, with games like AC2 and Dirt 2 loading immediately.
What's most troubling is the outright inconsistency of offerings from game to game -- Dirt 2 only offers a demo, for instance, while Batman: Arkham Asylum can only be rented, and Prince of Persia: The Forgotten Sands has no demo. Games have even been taken down since the service left beta, seemingly for no reason at all (Mass Effect 2 and Dragon Age: Origins, specifically). Pricing is thankfully merciful, with older games being offered at reduced costs (Assassin's Creed 2 is $40 through OnLive -- the same amount it costs through Steam and Amazon) and we've already had our first taste of an OnLIve sale.
As it stands right now, the service is -- perhaps shockingly -- running as intended. OnLive still requires a faster than normal connection (regardless of what the folks from OnLive might tell you), and it requires a wired one at that, but it absolutely, unbelievably works. Notice I haven't mentioned issues with button lag? That's because I never encountered them. Not during a single game (even UE3). Again, I probably wouldn't suggest OnLive for twitch, competitive shooters, but it'll do just fine for pretty much everything else. And hey, being able to play PC games on my MacBook? That's pretty magical.