Closed System (Walled Garden). I generally don't like this but must concede that the iPad is more "together" than Android. There are some things that I just can't do with the iPad.
Open System. A real plus for Android but has it's draw backs. There are more rough edges and I always do financial transactions on the iPad, for peace of mind.
Additional Memory. Android devices have card slots and general USB connectivity and the iPad doesn't. For photography this is a must have, so the Andoid wins here in my opinion.
Apps. Both have tonnes of apps, mostly rubbish. The important apps (or equivalent) seem to be available on both.
Size and Weight. My Galaxy 7.7" is so much lighter and easier to use away from home than the iPad. I haven't actually picked up an iPad Mini yet.
Battery life. I was always dubious about the claimed battery life of the iPad but it is MUCH better than my Galaxy Tab.
Screen. They're both pretty good. My iPad is only and iPad 1 I must admit. The Galaxy has a Super AMOLED display is excellent (and possibly hogs the the battery).
Photography. Android wins hands down with an open file system, card slots and USB connectivity.
GPS. Available on WiFi Android but not WiFi iPad. This is actually a show stopper for me. I can't think why Apple doesn't fill this gap. Perhaps it's the architecture of their chipset?
Conclusion. The iPad stays at home on the coffee table and is generally a bit nicer to use ( and doen't need GPS). The Galaxy tab comes on the road and is completely acceptable for ease of use. Neither can replace a notebook, nor are they supposed to. I wonder whether my next choice will be an Ultra Book or convertible, Windows 8 even?