Ok, so this is SP only, I haven't had a chance to try it out in co-op mode.
Overall, not bad. A far cry from great, but not bad. It runs well, the visuals range from passable to at times very good, although there certainly isn't a whole lot of detail to objects in the environment. On the upside, it does feel very clean though, which is nice after having recently played a few very aliased games. The jungle has a good amount of foliage, but it's also very static, and doesn't have much life to it. Overall, it's very solid, but it doesn't feel organic. Animation, another passable effort. Which is disappointing, because I really thought that FRD would excel in giving these characters "life". There are some cool moves performed by the rebels, but generally, it feels pretty artificial and conservative.
Now for gameplay. At first I felt crippled without a sprint button, but then of course I realized that nectar makes your movement a lot faster. That nectar bit is pretty interesting. It aids in target acquisition, but at the same time it distorts your view so it's not an automatic win deal. Guns range from average (Mantel assault rifle) to punchy (Rebel assault rifle). The Mantel pistol has serious oomph to it as well, nice to see (and hear). Grenades feel strangely lame to throw, but the actual explosive effect is pretty awesome.
Not much to say about the story content really. There's a nectar disruption part where I think you're supposed to gasp at the horrors of war, but in part thanks to having seen that sequence before, it didn't have much impact. There is one "scene" which does hint at this much ballyhooed maturity of the game, where a team mate is being visibly disingenuous about something that occurs off-camera, but that's about it as far as I can tell. Then again, if that stuff is what FRD claims it to be, it wouldn't be well communicated in a demo anyway.
So yeah, it's pretty alright. Coming straight from COD4, the gunplay doesn't feel as satisfying as I would have hoped, but I think that'd probably be the case no matter what game I played. I didn't play this with a dualshock though, and I suspect that rumble will add a lot to the combat feel.
Oh yeah, and the title music is quite nice.