- Templates. Even the custom ones look like something from 2002, and can instantly be identified as Blogger. While I’ll accept you can spot most Wordpress blogs, they look a darn sight better.
- Comments. Lets wait half an hour while the comment box opens. OK, lets start typing my witty and insightful comment, oh wait the comment box hadn’t finished loading so everything I typed has disappeared. What fun!
- Images. What size would you like your image? What are pixels? you can have them small, medium or large and like it.
- Speed. Or the lack of it.
- Lack of ownership. The inability to upload anything like a sitemap to your webspace.
- Word Verification. Have I mentioned that I can’t stand it? More to the point, half the time I can’t decipher it. Surely Blogger can create something better?
- Comments Again. There isn’t a list of recent comments to review, you have to go through each post to find new ones.
- Categories. Again, the lack of. Labels are useful, but not as good as being able to organise by category.
- No backup. Make sure you subscribe to your own feed, as I’ve mentioned before, because there’s no other way to safeguard your work.
I’m not going to do a top 10 for obvious reasons 
I write as someone who both reads a lot of Blogger blogs, and has also run a blogger blog as an experiment, and didn’t really enjoy it. I know it’s free, but really hosting and a domain name only costs about $80 a year, and you can make that back in a day or two with paid posting, so why stick with it?
Feel free to tell me where I’m wrong in the comments, and if you manage to make it to 9 (or more!) points between you, I’ll post them in a follow-up post, suitably linked up of course!