After using it for 4 days, here are answers to my own questions:
1) Operating system is quick, native apps are stable.
2) never used any other 5th ed. devices but it's not any worse than my n95. The main issue I had w/3rd edition is all the panning in the browsers, opera mobile has crashed on me already on occasion but other than that, it's stellar.
3) at half what I paid for the original n95, it's worth the $$.
4) Best:
- capacitive screen, respectable screen resolution
- camera seems better than my n95
- Ovi Maps w/navigation is very nice, it even prounounces street names
- all the ports are on the top, very convenient
- voice dialing was carried over from 3rd
- flash video player runs smoother than my n95
- easier to play facebook games via skyfire than my n95
- screen is readable in sunlight when set to full brightness
Worst:
- screen sensitivity has quirks, sometimes it goes off accidentally and other times it feels like what you are trying to touch is not at a sensor location
- email client (mail for exchange) is not improved, multi-select (mark) items is a multi-step process in both email clients
- the cursor that was present in 3rd in opera and the web browser is gone which means you can't roll-over things anymore
- can't lock the screen with the display on (prevent accidental touches)
- can only see 2 short lines of text while typing - this sucks!
- home screen has limited customization, choice of home screens displaying different content with space left over, how about just 1 home screen with combined content from both, it'll fit no problem
I have run out of memory using opera mobile, either it closes or nokia email closes, i did have to do a battery pull this morning as it got stuck in opera mobile.
so far my impression is that unlike my n900, the x6 is infinitely more mature in software implementation, however the screen and opera mobile 5th are the only advantages I've seen over 3rd edition