I have a couple of Pi2s here (to replace my existing PiB units), and also find the new ones a MASSIVELY improvement over the original. The ARM A7 core is a much more powerful processor which actually copes well worth modern computing demands, and as there are 4 of them, the device handles high demand well.
I have found myself using one as a "daily drive" without even thinking about it, something that was a struggle on the original. The 1gig of ram also helps.
As for emulating an Amiga? My guess is that A500/A1200 should be perfectly possible and satisfactory, something I will explore more if/when time allows.
