I have only done 4 batches, as I just started this fall, but 2 of them have been BB RIS kits. The first one I did with the dry yeast in the kit and it turned out very well after a couple months in the bottle. The second one I brewed with 2 smack packs of Wyeast Belgian Abby Ale II, and it just went into bottles after 3 weeks in primary (I'm still debating getting a secondary or not). Out of the primary, this beer has more complex, slightly fruity, but nicely-balanced character. I'm looking forward to drinking it, but am waiting several weeks. The first RIS fermented relatively smoothly, but the one with liquid yeast had crazy fermentation and needed a blowoff hose.
For my next two batches, I'm considering the Northern Brewer Wee Heavy and Nut Brown Ales. If anyone has brewed either of these, I'd love to hear about it.
I recommend the BB RIS.