I have the strap mounted version of the larger bag and like it a lot. Mostly I chose it because it was a good choice for carrying my camera safely. I don't use the fold out panniers a lot, but they are nice to have once in a while. I'd probably prefer the one with smaller panniers, but Topeak doesn't make all models in a strap version. My multi-tool and flat repair items go in the pocket on the back, leaving the inside available for other things. Even zipped up, I can put some small items in the sides.

It is quite large, even with everything zipped up, but it does hold a lot.