Keyboard input methods - this is one thing that has been bugging me since my switch to Mac OS X.
Actually it is more like 3 problems.
The first one is the way I have to cycle through input methods using Cmd+Space and Alt+Cmd+Space. I know 4 languages (Chinese, English, French, and Japanese) and as a result use 7 keyboard layouts/input methods daily (English, French, Simplified Chinese Pinyin, Traditional Chinese Pinyin, Cantonese Pinyin, Hiragana, Katakana). Cycling through the keyboard layouts and input methods is becoming tedious. I still prefer the Windows way, where I can assign a keyboard combination (e.g. Alt+Shift+1) to each keyboard layout and input method.
The second problem is the lack of official support for non-West-European input in the X11 environment. All attempts to build, install, and use UIM or SCIM have been unsuccessful.
Finally, the Traditional Chinese Pinyin input method seems to be a bit quirky. Sometimes it tends to feed out the wrong character. For instance, typing "zhang1" gives me "章" among the candidate characters, but if I select that character, the input method sometimes feeds the "杖" character instead.
Apple, please tackle these problems in the near future. I believe it will do you good in expanding your market in East Asia.