Early this morning (or late last night, depending on your time zone), the SQL Server Release Services team pushed out three new cumulative updates for SQL Server.
There are a lot more fixes in the 2008 R2 update – 43, by my count. In comparison, only 9 fixes for 2005 SP4, and only 2 fixes for 2005 SP3. You can draw your own conclusions from that data, particularly if you are still on SQL Server 2005 and are reluctant to upgrade.
And I hate to sound like a broken record, but to reiterate what I've said in other blog posts announcing CUs or service packs for 2008/2008 R2, none of the cumulative updates listed above are eligible for SQL Server 2008 (RTM, SP1 or SP2). I really hope Microsoft takes the confusion they've caused seriously.