I picked this up yesterday because the box said it was remastered, had new FX and scenes.
On the whole, the Five Doctors was something I wanted to like more but found very problematic, it's first problem being the lack of a certain Doctor.
The new DVD does some more logical editing, I didn't notice the new scenes however. The enhanced effects are nice but don't add too much, the Raston Robot sequence is still cheesy.
The new version uses less of Tom Baker's Shada scenes, I didn't mind that actually, it added nothing to the program.
Things I noticed:
The Dalek and Cybermen history with the Timelords is prior to when the Doctor first encountered them. Seeing as they refused to use them in the games.
Things that still bug me:
Jon Pertwee's "teeth and curls" comment about Tom Baker (on the commentary Terrance Dicks groans about that too, he didn't write the line)
Doctor #5 gives a really cold reception to Susan, shouldn't he have hugged her?
Doctor #2 knows his future, that makes no sense either!
All in all, it's an improvement but not earth shattering. I liked the commentary tracks a great deal though.