While I have not quite finished it yet, I would be shocked if any major revelations come along in the next couple hours of gameplay to change anything in this review.
Pretty much all the reviews are right. This game is awesome and awful at the same time. If you don't have someone to play it co-op, stop reading now and just don't buy it. With co-op, it's a JJ-Star-Trek-Themed Gears of War clone that does manage to entertain the same way that MST3K does, really.
As of this writing, the game is certainly playable and we've encountered only one major bug that required restarting a checkpoint. The most shocking thing when we started playing is the voice actors being the cast of the Abrams' movies, was not expecting that.
The gameplay is Gears of War light, for sure. You have your phaser and one other weapon. You can unlock upgrades and equip one from each of various skills, but most are pointless and after a couple levels the XP is equally meaningless. You get XP by Tricordering various flora, fauna, weapons, and, for some reason, stalagmites (because we certainly don't have THOSE on Earth). So if you are a lore junky you'll have boundless XP to use at least.
Primarily, you just cover and shoot your way through everything. The game is never anywhere near as hard as anything in GoW, aside from a couple boss segments that maybe aren't so much hard as questionably designed. When knocked into recovery mode, you seem to just get up on your own after a while most of the time if your partner is too busy being mauled to scan you back to your feet (as one does).
There are "stealth" sections which basically amount to 1: don't shoot anyone from the front and 2: use the crawlspaces. They are almost all, fortunately, completely optional and it is usually way easier and way more fun to just be a jerk and gun down everything. Again, the bonus xp you would earn from these stealth segments is largely pointless so that isn't really a factor.
The various hacking minigames are almost interesting and fairly harmless, but the flying / dodging minigames are largely annoying and needless.
To sum up: It's definitely worth the $3 I paid for it for the co-op experience with my brother. If you have someone to play it with like that, and you like GoW covered in Abrams Lens Flare Paint, then go ahead and grab it on sale. Otherwise, skip it.
1.5 years/3-year mission
P.S. The Gorns are jerks, seriously. Knock it off you guys.