Best place to get more detailed information is probably the AT-43 forum (linked from the Rackham site).
I have played it only a few times, but here it is pretty much dead at this point (that could very well be mostly based on the fact that the german distributor stopped supporting the product at some point).
AFAIK the game was pretty strong (not WH40K strong, of course) in France and the US mostly. Not sure how that is today. If they are on sale, that doesn't sound too good to me, though. I know that the supply of new stuff for the game has slowed down considerably with Rackham's financial troubles (I havn't followed whether they made it through, but apparantly they have, at least to the point that they still exist).
Basically, what you say sums it up nicely... fast and simple gameplay, but still some tactical variety (from my limited experience probably on a level with what WH40K has to offer, though the variety in units is a lot weaker, obviously; definitely much less tactical than a game like WHFB or Confrontation (3rd Edition; the new Confrontation is essentially the same game as AT-43)).
Bye
Thanee
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