I'm a long time Redrum devotee but as I started using fruity more and more I really needed a vsti drum sampler. The market is not terribly competitive, with DR 008 and Battery being the two main opitons.
I found DR 008 incredible ugly and unintuitive, but it is well liked on this forum. As for battery:
gui: basically good, oversized, and the 1 color flashing hit light would have been a bit more tasteful. I think this would be a better instrument with 10- 20 cells.(there are 54)
sounds: 20 very nice kits, i would have a liked real 808/909 kit instead of the more generic '80's drums'; but these sounds are around. Particularly nice is the reactor kit, with lots of funky noises. The accoustic kits are nice. I did not notice any multilayer patches, but I really haven't had it long.
sound quality: How can you f*ck up a drum sampler?-- oh yeah--Reason. No funky gain/grain issues here.
One big thumbs up; try the demo...Battery consisitantly crashed Sonar when I tried to create a custom drum map.