So far I have a mixed feeling for Vista Upgrade. I think microsoft went with the release of Vista a little too early. So I would call this release as a post-beta release. There is word of advice for users who are planning to upgrade to Vista from Wndows XP. Dont expect every application to work flawless in Vista. If you are prepared to experiment only then go for Vista Upgrade. Up until now, Vista doesn’t support a significant number of applications, including some that are critical to business operation. Many hardware manufacturers also haven’t yet released drivers that support Vista. And up until now enterprises are waiting for the release of a more stable Vista release (SP1) next year or in 2009 before implementing Vista. The resolution of application compatibility and driver issues in Vista may come too late. While application compatibility and driver issues should not be a big concern in one or two years from now, Vista deployment by that time may be less beneficial, especially if the enterprise has found no compelling reason to move over to Vista, especially if Windows 7 is on the horizon. But on the other hand individual users can still go ahead with the upgrade is they want to reap some enhancements in security and the overall Graphical User Interface changes Microsoft incorporated in Vista.
In my personal experience XP still holds an edge over Vista in terms of stability and compatibility. I have heard from people that they dont prefer Vista due to its huge memroy consumption specially with its indexing feature. Even on a machine with 2GB RAM it hogs up memory very fast. Iam desperately waiting for the release of SP1 and hope that these issues will be resolved.