It does feel faster and benchmark faster than the 3970. Since the PPC2003 OS doesn't really offer much in the way of optimizations for XScale, I suspect the speed is about 65% due to the newer PXA255 processor that has a 2x faster memory bus than the PXA250 used in the 3970 and other architectural improvements in hardware, and 35% due to the new OS. It's interesting that benchmarks for the new iPAQ 5555 so far have been slower than the 2215!
Compared to the performance of the 3970, did you feel the 2215 was much faster? If yes I wonder how much of that could be credited to the 2003 OS and how much an upgrade to the 2003 OS could improve the 39XX models?