Is There Any Common Issue shows from Application Side after SQL Service Pack 4 had been Patched?

Hi All, 

I am planning to patch SP4 on a SQL server 2005 standard edition (production server) since the SQL version is 9.0.4053.00 which no longer supported. So far all the SQL instances  in our dev/staging servers had been patch to SP4.

I just would like to know is there any common error/issue(s) show from application side after SQL service pack 4 had been patch?

As I know, if I rollback to previous settings, I have to re-install the SQL instance and patch till SQL version 9.0.4053.00 again which is a hard pain. Since need to patch in production server, so need to be more aware of the rollback process and this may time consuming. 

Thanks and hope can hear some feedback here. 

Best Regards,  

            Han