On the other hand, Qt 5 is already here. Porting existing apps from Qt 4 to Qt 5 is actually easier than it was to port Qt 3 stuff to Qt 4. Take a look at this Qt project's wiki page for more info. Also pay attention at the links at the bottom of it under "Recommended Reading".
Some time ago I blogged about the 5.2.0 status in Debian experimental. We currently have it in testing with a much better status:
And we also have 5.2.1 in experimental with an even better status:
|Note: qttools is FTBFS in armhf just because of some symbols changes, it will be fixed on the next upload.|