Being surprised at how it looks compared to the prerendered hype of the website might say more about the website than the ingame visuals. The website is very pretty and, whatever you say about prerendering, it seems to work well to attract people and to make them take BAR more seriously.
I think the visuals are decent. The maps are very good and something I think could be done for ZK. High quality map visuals seem pretty important when the map takes up almost all the non-UI space on the screen. The special effects (CEGS) also show that someone has gone through the effects and put an effort in to make them consistent and look good. I think it shows everyone who has moaned that the technology is a bit ancient instead of improving the ZK effects that all it takes is a bit of time and attention to detail, not the next big rendering overhaul. The units seem nice and consistent but I am concerned that they've sacrificed being able to recognise the units at playable zoom for the sake of visuals. If someone were to remake the ZK models then I'd want them to be high quality and at least as recognisable as they are now, which would be quite a feat.
We'll have to see where the gameplay goes. I'm not sure how close each of the developers thinks they are to being done.