Got it tonight. Played a couple of missions with each species.
Predator:
Easiest of the bunch. Cloaking ability doesn't drain your energy reserve (like in the underrated Concrete Jungle game), but the PlasmaCaster does. Every time you're cloaked and then strike? You become uncloaked. A little awkward, but whatever. The amazing jumping ability and thermal vision, as well as the distraction ability (you play a recording of somebody's voice, and whatever Marine you selected to distract will come over in the direction you chose them), help with killing the Marines, but the Aliens are a little bit trickier. Getting past the Sentry Guns is a bit of a bitch if there's not much room for jumping because they'll shoot you when cloaked, too.
Alien:
Moderate difficulty. Incredible speed and the ability to crawl on the walls and ceiling, as well as run into the vents, is a massive plus, but I'm surprised there was no acid spit feature given that it's fairly accepted canon that the creatures bleed and spit acid. Health regenerates over time, but it goes quick when against Marines. Haven't gotten to face a Predator yet, but I'm going to imagine that it'll be a bit difficult due to them having better long-range weaponry than the Marines. Fun, but a bit disorienting since your view is similar to the Alien's view in Alien 3, an almost fish-eyed one.
Marine:
Hardest of the bunch, considering everything is pitch black and your Shoulder Lamp does fuck all. You start off with the Pistol and have to kill a few Aliens with it, but then eventually find a Pulse Rifle, but only about half a mag of ammo (and no grenades). Creepiest/scariest levels, too, since your Motion Tracker will randomly go off, but you won't be able to see anything until it's right on top of you. Like with the Alien, I've yet to encounter the Predator, and I'm not looking forward to when I do considering how easy it was to kill the Marines as the Predator.
TIP: Don't tap the fire button when using the Pulse Rifle, hoping you'll get some quick bursts like you would in MW2 or any other modern FPS. Hold it down, and it will do its thing (pulsed bursts). Aim for the head, obviously, for the quickest and easiest kill. Pistols do jackshit, as it took a clip and a half to put down my first Alien.
Modes:
Since I don't have Live yet, the only mode available is Single Player Survival, which is just a gauntlet run with you as a Marine, armed with a Pistol and a Pulse Rifle, as waves upon waves of Aliens - each wave stronger, faster, and greater in numbers than the last - close in on you. A fun time, though.
Graphics:
Perfectly acceptable, although they look more like something that would have stretched the capabilities of PS2 or the original X-Box than the current gen stuff, specifically MW2. Great use of shadows in hiding the limitations, though, and the designs of each area I've encountered so far (Lab, Colony, Jungle) is perfectly taken right from the movies.
Sound:
Weyland Bishop, likely best known as Bishop II in Alien 3 (and a descendant of Weyland Bishop I in the first AVP flick), is the head honcho of Weyland-Yutani, which means one amazing thing: LANCE FUCKING HENRIKSEN. Other voice acting seems solid, if a bit generic for the Marines. The sounds of the Marines' weaponry, the Aliens' hisses and growls, and the Predators' clicks and cloaking noises are taken directly from the movie (I think the sound of the Pulse Rifle just may be one of my favorite sound effects in any movie), but the Predators' PlasmaCaster sounds more like a generic laser from a generic sci-fi flick than it does the quick CRACK~ like in the movies.
Overall:
I can't give it a solid rating yet considering I've only played it for maybe a couple of hours total, and don't have the capabilities of doing online play, but it's looking like an 8-8.5 thus far. WAAAAAY better than those pieces of garbage Alien Trilogy and Alien Resurrection for the PSX back in the day, that's for sure.