All I can say is, "wow!"
My all-columbus APA is without a doubt the best beer I've ever brewed.
The Columbus flavor and aroma are a little intense right now--they'll probably mellow a bit (it's only been carbonating 8 days), but I might consider cutting the columbus with something a little softer--maybe willamette--in the flavor/aroma additions next time I try this.
But I'm thrilled: clarity and color are fantastic, nice hint of maltiness under the hops.
I bottled my second AG batch--a wit--just now. My only concern after tasting it is that it tastes a bit BMC-ish, but I'm sure it will have more character after bottle conditioning. The color (extremely pale, slightly grayish and cloudy--a lot like Hoegaarden) would be pretty-much impossible to achieve w/ extract.
I'm definitely hooked--the downside is that it's hard to find time for brewing AG batches.