It's a decent bag for what I do with it. Probably a good thing since it's the only actual camera-specific bag I own.
I got my REI dividend one year and didn't know what to do with it. This turned into a rare-for-me impulse buy. I don't remember what I actually paid for it: REI is a great store but has some insane mark-ups, and I can only imagine that B&H or Adorama or Amazon would have been a lot cheaper.
I normally carry a 50D with 24-105L centered, ready to pull and shoot. Off to the side on one side is a Speedlite 430. On the other side is a Thrifty Fifty. The mesh flap pouch carries a few spare CF cards, and the low "front" pouch carries spare batteries.
Limitations: It's not a huge bag. If I left the Thrifty Fifty attached and wanted the 24-105L set aside, I don't think I'd be able to carry them securely that way. And the 24-105L is about the limit of how large a lens can be kept attached and carried securely. I also don't think it would accommodate a second lens that's much larger than the Thrifty Fifty. My 3.5-5.6 70-300 would never fit in there, I don't think.
Short, short version: if you just need your walking-around camera and some odds and ends, you could do a LOT worse.