My initial reaction after a map or two was one of utter confusion. In the beta map, the strogg are defending the map and the GDF are attacking it. There are a series of progressive missions that have to be completed/prevented for whichever side to win the map. However, different classes are needed for the different missions, and it wasn't immediately obvious what to do. From the Strogg's point of view, it was even more confused. Not least because the equipment isn't the standard fare that you get in, say, Beef. However, by the end, I felt I had a grasp of what was going on and therefore it all made a lot more sense. Many of the tools/vehicles etc will be a lot simpler once I have the manual to read too.

The map used in the beta is pretty small, and doesn't appear to have the teams swap objectives, but hopefully bigger maps with more varied missions will appear in the full game, and the pace should be accordingly less frenetic.
I think I stuck everything up to high and it worked perfectly smoothly on my machine. Lag was a bit crappy, but I think that's due to it being a beta still. Overall, the graphics seem pretty good though.
The game had a feel not dissimilar to Beef, and once I'd wrapped my head around what was going on, I started liking it a lot more. I don't love it yet, but I haven't been put off it yet either. Roll on the full release!