"Incomplete, dont buy yet."
The engine, graphics, etc. all look great (albeit with high requirements) but the gameplay is nowhere near complete:
There is an overall feeling of not enough variation in the units and sides, the 3 campaigns are each only 6 missions long, the skirmish AI is awful, the touted feature of 'Coordinated Assaults' doesn't actually work.
The biggest reason not to buy this yet is that the tools that were supposed to be come with the game are nowhere to be found! The fan community is moving incredibly slowly and as of 25/Feb/07 there are about 5 custom maps and 3 unit mods announced on the web.
Seriously, don't waste your time trying to play this until they've patched it and the fans have released some decent unit packs. By that time it will probably even be cheaper :D