First and most importantly:

2.0 Does NOT support ANY HOMEBREW!

now that we have that out of the way.  If you have 1.50 I DO NOT recommend an upgrade, if you have 1.51, 1.52 I would upgrade because most people with 1.51 and 1.52 will be and thus there will be a good force of people trying to put homebrew on 2.0 .  But think this all out on your own

To see what 2.0 has or to download it visit here.

http://www.us.playstation.com/psp.aspx?id=SoftwareUpdate