Same for me, no mypaint icon in the menu.
When starting from the terminal it warns: "Warning: Where have all my icons gone?" followed by a theme search path.
Also the "mode for input devices" is set to disabled on first run. Had to set it to screen manually.
The brush selection window has strange characters between the brushset names.
Oh and when opening a file I get a python warning in xterminal from filehandling.py line 204: which reads something like HildonFileSystemSettings has no property named 'hour24'