Version 5.5.3 vs 5.1.1


I am happily using version 5.1.1 since it was released, and never turned back. When 5.5 was released, I remember there were some complaints about it.

I lost track of what happened later, and would like to ask if somebody can suggest if its a good idea to update to 5.5.3, and whats the main difference with 5.1.1

In case I will update, is there any chance that any song produced with 5.1.1 can have even the slighiest problem with 5.5.3?