I know I might be stating the obvious but, after install, please reboot your phone. Then try it.

The various "bugs" people are describing (including the slowness) are what I saw when running it straight after install.

After reboot, it is not really slower than MM9 and it isn't leaking memory anywhere. The experience is pretty good with MM10.

I would like to have seen a free-text quick search for a destination (such as that in Ovi maps) but, other than that, it's a nice bit of kit.