I have not heard of any customers having any issues upgrading. We'll have a maintenance release (10.0.1) available shortly (unknown timeframe) to address items that have come up as you might expect, but there are no major showstoppers that I know of.
Thank you very much Russell. One more quick question what you will recommend to go Tableau 10 or tableau 9.3 . I have seen that when ever we have a discussion with tableau support for a issue they used to guide us to move to the some other version. if we do upgrade i.e means we are moving 30 projects, 250 dashboards, 200 data sources, many subscriptions . These all should not be affected.so your suggestions are very important for us.
Well, my response was very timely. Only a few hours after my post the 10.0.1 maintenance version was released. Tableau 10 is fantastic and I can't give you any reasons to stay on 9.3 if you have the opportunity to upgrade.
I will strongly recommend that you read through the Server Upgrade guide, especially the upgrading section. The content, users, subscriptions should all transfer seamlessly. Depending on what version you are on now, there might be some tweaks that need to be done on the security integration (OAuth), API or embedded pages, WDC (web data connector), or Vertica. We've had many, many customers upgrade smoothly from previous versions.
As with any upgrade, it is recommended that you test your specific scenario on a development server to make sure the upgrade goes smoothly. If you would like to discuss any other specifics, please post them here or contact your Tableau representative.