I have 7 hours logged into my steam account on it, here's my opinion thus far:
This is an action
RPG. Super emphasis on the RPG. If you don't put points into an ability (like stealth or a type of gun or hacking, etc.) you're pretty much useless at it, forcing you to tackle issues another way. I like it a lot. It reminds me a great deal of Deus Ex and Vampire The Masquerade, and I mean that as a compliment. Though I can see how some parts of the game would be VERY difficult if I didn't play through my first time as a more combat-oriented character (how stealth characters get through boss fights, I haven't the faintest idea), I'm looking forward to seeing that on future playthroughs.
The amount of choices and cause-effects this game has is, frankly, staggering. Every mission you do, the briefing at the end often lists a half dozen choices you made and the potential consequences of those actions. EVERY speaking character you meet has a rep bar, and a lot of them look like they can be major characters or just stepping stones if you so choose. It's pretty ridiculous, honestly.
The gameplay itself is good to decent, at least as a combat-focused character. I mostly just shoot everything but once you get a few ranks in your chosen gun(s) the gunplay is pretty fun. The cover system is wonky at times but it gets the job done, though many enemies aren't content to just let you sit there anyway so there's always a lot of tension in the fights. I still have fun punching people in the face and blowing them away with a shotgun, or shooting them a ways off with an AR. The special abilities are also cool, though I think I'm on my way to being overpowered if these enemies don't take some serious levels in badass soon. The assault rifle ability of being able to lock onto enemies by pushing a button is like whack-a-mole with high caliber bullets.
Story is interesting, though I wouldn't call it exceptional by any means. It is also shaping up to be pretty basic, corrupt executive working with bad guys to make the Dollar Bills and Take Over the World, yadda yadda, though I wouldn't be TOO surprised if it's only supposed to look like that is the way it's going. The supporting cast is decent as well, and Thornton is quite the charming smartass if you want him to be

Voice acting ranges from passable to good, no stand out performances on either side of the spectrum.
As a final, and most important note...
I HAVE NOT SEEN ANY BUGS. I REPEAT. I HAVE NOT RUN INTO A SINGLE BUG.
So, there's my opinion, 7 hours in. At the end of it, and probably after a couple playthroughs (I guarantee at least 1 more, as a Jack Bauer/pistol whipping badass who tells everyone to F-Off), I'll say it's worth a rental at least for just about any rpg-action fans.
The Madman said:
OBSIDIAN IS THE REINCARNATED FORM OF TROIKA, AHHHHHHHHH!
My god this was a long post, I do hope at least one person reads it!
I just got finished playing Bloodlines again a couple weeks ago, bloody great game still. Also, those are some rather strange coincidences aren't they? Far worse studios you could be reincarnated from.. Anyway, interesting post
edit: Fixing stuff.