Edit: Update Rollup 18 is now available for Exchange 2010 SP3 see the post Exchange 2010 SP3 Update Rollup 18 installation tips.
On 15th September Microsoft released the Exchange 2010 SP3 Update Rollup 11.
I’ve installed this on my test SBS 2011 server, it took just 7 minutes 45 seconds from start to finish, by far the quickest update yet and my test server isn’t very powerful, so I wouldn’t expect it to take much longer than this in production.
The new update has been available for a few weeks now, and I have not seen any issues reported with it so I suspect it is safe to deploy in your production environment.
If you are doing a migration to Exchange 2016, then Exchange 2010 SP3 Update Rollup 11 is the minimum version that will be supported in a coexistance environment.