Well... It's a solid autoplatformer. Nothing groundbreaking, but if you're not averse to games like Prince of Persia 2008 or Uncharted, you might find the game to your liking as well. Funnily enough, the platforming segments are even less interactive than widely panned PoP2008 (single button+stick for directional input).
The environments, especially in the opening chapters were simply beautiful. Great use of color, lush vegetation, decayed civilization. Personally, out of all UE3 games I've played so far, I believe only Spec Ops: The Line could top this game graphic/design-wise. It gets minus points for some rather questionable texture work (at times you would think UE3 glitched out and stopped loading mip-maps of the texture after the first one) and the later levels, especially the junkyard ones, which simply didn't look as nice as the opening segments.
Story was... there, I guess. Doesn't make much sense if you try to piece it together, but oh well. It's an action video game, if I wanted a story that wouldn't insult my intelligence I'd read a novel. Characters were all right, mocap work very impressive.
Unfortunately, where Spec Ops was a really solid, (un)pleasant experience, I can't say Enslaved was as stress free. There is a well known bug with the game, which results in it freezing randomly once in a while. I'm not sure if you can call it stuttering when the freeze can last up to 30 seconds, and can be almost immediately followed by another one lasting as long. Also, shadows during cutscenes were beyond broken for me.
As you can imagine, this completely kills immersion, and is downright infuriating if you're hit with this during a fight or a timed platforming section. I hope my neighbors won't think badly of me now, with the amount of swearwords I uttered while playing (or rather waiting to play) the game.
DLC was a completely separate thing, both story and gameplay-wise. And I do mean separate, where the main game had mostly QTE, platforming, fights and bits of shooting, DLC is pretty much a cover-based forced-stealth puzzle game. Reminded me more of an Oddworld game, truth be told. Later sections devolved into shooting galleries, which is a bummer.
Overall, both the main scenario and DLC are a good way to spend a few hours. Your enjoyment of it will be largely dependent on how much the bug I mentioned will affect you, and, well, how much you like interactive movies.
Price I'd pay for the game and wouldn't feel ripped off? $3.75 tops.