I'm in the process of migrating from MT to WP and haven't explored all the capabilities or plug ins of WP yet.
However, whilst it's still fresh in my mind here are two capabilities/plug ins I would love to have seen in MT:
1)' Adding' (dynamic) comments to a static page. This would be a really useful function for those of us who have an existing site with standard HTML pages but would like to get user feedback on those pages. Rather than changing everything over to php and installing some sort of comment script it makes sense to keep existing incoming links and keep the existing site. It also makes sense to use an existing 'comment system' as incorporated into WP as this will be highly functional and will be constantly upgraded.
I made a simple test page using MT a while ago (I got rid of the page once I'd made the decision to migrate to WP) using the very basic principle of adding a SSI into the bottom of a standard HTML page. In MT I then created a blog called 'Comment' and tweaked the page setup so that all pages were stripped of their html, head and body tags.
Obviously for every html page that I wanted to add a dynamic comment facility to I had to create a matching nominal page in MT.
So if my Html page was 'Mypage.html' I then created a matching page in MT called (for ease) 'Mypage' and used a SSI to include that 'page'. The MT page was stripped down to its bare essentials and was basically just a comments input box and resulting comments .
It was a bit of a bodge but it worked. My test html page ended up with my test comments and an 'add your comment' function at the bottom of it, and I was able to admin. these comments from within MT - I'm sure there would be a more elegant and user-friendly way of achieving the same thing in WP but I don't have the skills.
2) In MT one thing that really annoyed me (maybe there was a solution but I didn't find it) was that you couldn't see all the comments 'open' at once. Instead, you had to open up each individual comment to see whether or not it was (as suspected) spam. I wonder if WP has the facility to see all the comments 'open' at the same time?