I'm using TeXstudio 2.5.1 with Win7-64.
What I'm really missing is the auto completion of (long) words, the user has already written in the current document. Writing s.th. like 'trans-impedance-amplifier' a dozen times in a text is awful. Writing it out once and later just typing 'tran' and pressing Enter would be really alleviative. Surely it would make sense to limit the list of suggested words to entries longer than 5..6 characters (maybe adjustable in the options).
I know that using a word very often is not a good writing style, but in technical/science texts it's not usual to use synonyms.