The latest version of Ubuntu is heavily based upon Unity environment. Unfortunately Unity has no track record of playing nice with existing gnome programs. For network applications such as VNC, Unity crashes the program with whole bunch of errors. These crashes are observed occasionally in the Ubuntu 11.04 (Natty Narwhal) release, and most certainly in the latest beta 1 release of Ubuntu 11.10 (Oneiric Ocelot).
If you have gotten comfortable with Ubuntu and want to continue using Gnome as the main environment, you can do so by using Linux Mint 11 (Katya). It has the same repositories as Ubuntu and you can even use the ubuntu-restricted-extras and build-essential packages which lets you obtain some of the fonts, codecs and libraries that Ubuntu fetches for you.
Ubuntu is starting to put more emphasis on making their release into an eye-candy, at the cost of reduced functionality. Having used Ubuntu since Dapper Drake days, its sad to ditch it for another distro. IMO Ubuntu 10.04 was the cleanest distro they put out – things have been going downhill after that. Linux Mint on the other hand picked up at the point when Ubuntu started to go dysfunctional. It has everything that Ubuntu should have been. There isn’t much to write about Mint 11. Its very similar to Ubuntu 10.04, has a newer kernel 2.6.38.xx, clean graphics, and the same repositories as Ubuntu. The transition is very easy, and things look a lot more neater in Mint.
To recap: If you are currently using Ubuntu and are afraid to upgrade to the 11.10 release, your fear is quite justified. Make a backup of your /home folder and go for a clean install of Linux Mint instead. I moved to Mint about a month ago and have had a rather smooth sailing so far.