I had been asked to comment on the move after I had some time to get used to the features.
There are two important things to think about in the move: (1) Do I want to go through the work? (2) Is it worth it?
I should state at the start that I have no animus toward Blogger or Blogspot. Every server has outages from time to time and glitches in functioning. Considering the huge number of users and amount of traffic that the blogspot servers receive, I'd say that it's remarkable that so little goes wrong.
However, when you're with Blogspot, you have to sign up for endless add ons to make things work as you wish. You've got to go somewhere special for RSS feed, you have to add on a commenting service (if you wish comments) and you need to add on a traffic counter. (Something you also need to do on MT if you aren't running your own server.)
The advantages of MT are manifold. You can edit multiple entries at a time, you can categorize, you can display your archive in any number of ways. The style sheets and templates seem easier to parse so you can change styles pretty much as you wish. You have trackback ability and pinging of entries.
I had long looked with great desire at the cateloging function available on MT--it is every bit as wonderful as I had hoped, and the ability for me to view my archives by category is beyond mere dreams wonderful. I am slowly (very slowly) cataloging each entry (I transported over something like 1680). But the value of this function made the move worthwhile for me.
So ultimately I'm at MT for the greater control it gives me over my materials and what I am doing. I really like MT now that I'm used to it and think that there are benefits that everyone would enjoy. The editing seems simpler, the interface as clean, the possibilities greater. I don't use many of the possibilities because I find some of them aggravating to read--for example, I don't excerpt my entries. It would probably be an advantage to readers were I to do so, but just as I hate news stories continued elsewhere, I'm rarely inclined to load another page to finish reading an item. It's just me. But that option does exist on MT.
All in all, I would say that I am ecstatically happy with MT and would recommend it to all who need the power. If you've been doing blogger for some time now and are content with its features, there is really no need to go to MT. In fact, but for the cataloging features, I would probably still be with blogger. And with ultra blogger, it may be possible to add those on.
Anyway, MT is very, very nice and Stblogs.org is a lovely place to be.