This morning I have installed Exchange 2010 SP2.
I must say it was (as expected) a very straightforward process.
The setup wizard passed most pre-requisites first time.
The only pre-requisite which failed was the UM Language Packs.
As I work in the UK I had the en-GB language pack installed.
This was easily done using command prompt in the
<EXCHANGE SERVER INSTALL POINT>\bin directory
I ran;
Setup.com /RemoveUmLanguagePack:en-GB
Then continue with the install.
Once completed re-install the language packs, the desired language pack can be found here;
http://go.microsoft.com/fwlink/?LinkId=231660
Download the correct one and run it and you will have your desired UM language pack installed.
The only other issue I came across was the
“You must close all dialogue boxes before you can close Exchange Management Console” problem.
A quick google pointed me here;
http://smtp25.blogspot.com/2011/07/you-must-close-all-dialog-boxes-before.html
This seems to indicate some problem with IE9.
I added https://localhost to trusted sites in IE9 and all worked fine.
So as said the install was all good and was straightforward.