Hi,
i have a slight other feeling as Arvind. In my eyes stability has been improved with 4.1 SP02.
One thing where you can see this dramatically is WebI. The Java viewer is now much faster and you get quicker response. This is because they changed the process of when and how the vairables pop up as Paramters.
So if you use WebI an Update to 4.1 SP02 is very recommended.
If you update please follow the Best Practices and you will be fine.
http://service.sap.com/sap/support/notes/1757132
Regards
-Seb.