You should note that you can't upgrade directly from LTS (long term support) release to nonLTS release that is not a next release, you'll be needing to upgrade first to 10.10, then 11.04 and then to 11.10. However you'll be able to upgrade from 10.04 to 12.04 directly, because 12.04 is also a LTS.
Generally you'll get newer versions of packages. But if you're satisfied how 10.04 works and don't have explicit need for example newer version of php/apache/mysql you'll be fine and perhaps should wait for 12.04. I also have 10.04 on my server and am not thinking of upgrading any time soon.