Sarah Blow is asking a number of questions about Windows CE 5.0
1. Does CE 5.0 support TKIP?
2. How stable is the new CE platform, are there any known issues that I should be aware of?
3. What components have been removed that were in CE 4.2?
4. Are hotfixes being released and installed in the same manner as 4.2?
2. How stable is the platform. That's an interesting question, stability can in many ways be similar to "real time" - you determine the real-timeness or stability of a system through testing - is the core o/s stable, sure, should you test your system to prove the stability, absolutely.
3. What components have been removed from Windows CE 4.2 ? - There's a useful document comparing Windows CE 4.2 and 5.0 features here.
4. Hotfixes - QFE's are released in the same way as Windows CE 4.2 - a list of Windows CE 5.0 downloads (including QFE's) can be found on MSDN here.