I couldn’t help myself… I bought a Raspberry Pi 2 (RPi2) to evaluate.
The RPi2 has 1GB of main storage (double that of the earlier RPi B+), and a 4 core 900MHz processor against a single core 700MHz process in the the RPi B+.
My preferred distribution for RPi is currently Raspbian, so the evaluation used that distro.
As I understand it, Raspbian selects a choice of armv6 (Rpi) or armv7 (RPi2) kernel at startup, but the rest of the system is armv6 code (and therefore does not fully exploit the enhanced instruction set of the armv7 processor).
Having copied the SD card from a RPi B+ system, it loaded and ran with no problems and was obviously a snappier at the command line interface.
A comparison was made of the time to fully build aprx, a C application of about 24,000 lines of code. Build time was 98s on RPi2 vs 258s on the RPi, 2.6 times the speed. This is a useful improvement, and a little surprising given there is no optimisation for RPi2 other than using the RPi2 kernel.
This same task takes 21s on a rather old low end 2.6GHz Intel single core destop computer.
Given that there is little difference in price of the new board, it seems a significant value improvement and the performance improvement might drive replacement of some existing RPi B+ systems.