Particularly if you’re in the IT industry.  And the main reason I like it:

Full-version software for evaluation – without time limits – including Microsoft operating systems, servers, and Office System software.

Now when I was working for a large IT company, I got that benefit for free, via our corporate Technet / MSDN / Enterprise licensing agreement.  But now I’m not, I had to find another way.

And that other way is: TechNet Plus.  One of the great "secret" deals from Microsoft.

Worth every cent, as Kevin Remde explains.
(if you visit via Kevin’s site, as a new subscriber you can get a 15% discount until June 2009)