It is just a 10v10 in the mid usually. Ranged classes are at a massive advantage and if you are one of the few mellees good luck. You will have to play very defensively. You will get decimated into oblivion. There is very little option for small skirmishes although they some times break out.
Not much strategy or feeling as though you pulled out an awesome win like in any other BG. Personally not a fan of it.
May be better for BG blitz with the lower amount of players. We will have to see.