there is another thread or two about this dialer, just search, but to answer your question: specifically the smartdialing issue. no one has been able to figure out why (i don't think) in wm5 after the 1st incoming/outgoing call you lose the functionality of smartdialer until you soft reset, which kills it immediately. I also had same issue as you, not able to uninstall. however, try soft resetting first, and not entering the phone application - go straight to settings -> remove programs and see if that works.
as for other issues, I've noticed my audio from a reset (phone_on sound) is gone and doesn't play during the startup screen, and entering some folders now takes 3x-4x as long in file manager, and its not just due to file size or # of files.
its a pretty skin, but flakey. right now I can only see the numbers on the dialpad, even when I press a # it doesn't display, so I may have to hard reset
this is after an uninstall, btw
user beware!