I'm not really sure how long the batteries last (and it'll depend what type and possibly what effects used), people seem to suggest about 3-5hours, which seems about right. Which doesn't amount to many sessions if you sit and play for hours at a time: don't plan on feeding a Pod single-use alkaline batteries, because you'll need a big box of them. Not too much of a problem for me as I can usually just unplug it and use the amp if it runs out while in use. If you have a spare set you can just swap over when they run out, or use a DC supply. Settings are actually quite easy to adjust on the unit though I don't like the multi-function-knobs-jump-to-their-current-position-when-adjusted operation, but that seems to be pretty common across manufacturers.
I do like the Mustang. They're physically big though, I think it's the biggest among comparable amps. It's not AC30 big, but it is still pretty sizeable. Adjusting effects is also a bit of a mystery (no display on models I&II, need a reference for selector knobs), I leave it plugged in to the computer and use USB if I want to edit effects (also means recording is just a case of pressing 'record'), but most of the time I actually just use the presets. Hadn't really tried it through headphones until doing the comparison with the Pod, and didn't do a very scientific test, but it has a nice rich sound.
Did try the Mustang against a VT40 in the shop, and picked the Mustang mainly because I couldn't get the VT40 down quiet enough for what I needed. The Vox stuff takes a very different approach to the controls and, for the amps at least, everything is meant to be adjusted through the panel and there are sufficent dials to let you do that, though a (little) bit of practice would be needed.
Edit: I'd hope a shop would let you try a ToneLab if they had one, a Pod maybe less likely as it's a smaller item and they might find fiddling with batteries and things a hassle.