Here's the Mini in the two-piece case, the way I normally have it. Also in the picture are the keyboard and, for reference purposes, an original iPad in a beefy case.
Here's the Mini with the keyboard attached (alas, both parts of the case must be removed; I was hoping the impact portion could stay, but it can't). A dollar bill is included for scale.
As with its older and bigger sibling, the iPad mini fits into a slot on the keyboard. The connectivity is via bluetooth and I expect the power consumption to be quite minimal, judging by its predecessor (if it isn't, I would assume a flaw in the one I got, not a design flaw). The punctuation keys are very tiny, even compared to the letter keys. I understand the design tradeoff involved and endorse it, but it can be a little bit of a problem typing.
As people have observed with netbooks and similar, small, keyboarded setups such as this one, they don't straddle the legs quite as stably as a classic laptop. Alas, this thing wobbles a lot when balanced on just one leg. It works fine on a table, or a lapdesk, so as an airline option it should work great with the tray, or more generally on an armrest (altho you'd get a heck of a crick in your back after a while).
I'll update this if/when I travel with it and attempt to write anything substantial with it. I'm typing this on my laptop. ;-)
ETA: For a much higher quality review, produced in context with reviews of competing products, see: