I was going to write up a nice succinct description of the reasons and then I read SharePoint Joel’s and said, these will do just fine! Thank you again Joel.
In quotes as it was copy/pasted with respect. Go read the rest at Joel’s blog.
It’s nice when things happen as expected.
Five No Brainer Reasons to Install SP2 (When you are ready!!!)
1. Performance Reliability/Stability Fixes
2. Browser support for IE 8 and improvements in tier 2 browsers (Firefox)
3. Reliability improvements in Indexing and Index Corpus
4. Security Improvements
5. New STSADM Commands including some to fix corruption and relationships (orphaning)