I always wait to a x.x.1 version to upgrade a production site. I am one of the people who were waiting for this update. You can take a look at the forums and will see that there are people with problems. Most of them found a workaround, others no. I know that this is apersonal position, but I know most experience people do the same (test and wait)

One of my problems (at a fresh install of 4.4.9) is the white space remover (Activated by default) and images inside media module and some custom modules. Another one for me as a developer (3r party modules) is that the GetModuleByDefinition is not working like before:

http://support.dotnetnuke.com/issue/ViewIssue.aspx?id=4763

As always, you can try to find a workaround a start using the new 4.4.0 (Is is really good), but if your production site is receiving

People testing the 4.4.0 version did a great job testing and finding lot of bug that the core team fixed before releasing the package, but as you may know, nobody is perfect and some issues were present after the release

check the the following site to see the status of the reported issues:

http://support.dotnetnuke.com/Issues.aspx?m=1&PROJID=23

As a suggestion, do the upgrade by using a shadow copy of your site and then test everything. If no problems with your instance, then go ahead. There will be cases (Depending of your site configuration and module set installe) that no problems will be present.