These are simply my thoughts after playing with the new site for a couple of hours.  I'm having some ups and downs with the new engine so far. I'm sure I'll come to love it and there are probably some good workarounds to several of the issues I'm having.  I'm posting this here so that other bloggers could potentially help out or find this information helpful.

• Wow, new skins to play with! ... and they seem even more customizable!
• Recent Posts feature broken :-( They fixed the feature bugs that let me put recent posts on the side by stripping anything but really basic HTML in the blog text entry fields.  I must find a new way to make this work. I had a lot of clicks from one post to another after I had enabled this before. 
• Blog Search! Cool, no more hacked in msn or google search.
• Category RSS Feed Links Changed :-(  If you were subscribed to any of my individual category feeds you aren't any more.  The category feeds have been updated from the category/####/rss style to the main rss.aspx with a category argument ala rss.aspx/categorized=####.  I found out about this since I was consuming feedburner versions of other MSDN blogger feeds that had broken because of this.  So if you are using feedburner on your catagories... you'll need to update feedburner with the new links.
• The feedback moderation UI is MUCH better!
• Logging in as your blog name could be bad.  Now, if I'm logged into my blog and I go to leave comments it doesn't let me say who I am. So I can't leave comments as "Josh" unless I log out. "jledgard" isn't bad, but there are other people with less name-like blog names this will hurt worse for.
• Richer Feedback Moderation options! Here is how I'm configured now: You can leave comments on all my older posts! No more 30 day limit to conversations!  Moderation is turned off for users who are signed in. Anonymous comments will still be moderated by default. I would still like to have my feature suggestion of a comment free-for-all for X days and moderation by default after that time. Seems like, by default, our blogs have been set up so that no anonymous comments have been enabled. If you would like your favorite blogger to change this I suggest you send them mail saying you don't want to have to log in to leave them comments. 
• No "in-blog login". :-(  Seems I have to go to the blogs.msdn.com home page to log in then navigate to my blog to hit the admin UI.  Extra steps that seem unnecessary.
• Friendly post URLS! Looks as though I can name posts for friendly URLs like blogs.msdn.com/jledgard/mypostonfoo.aspx. This should come in handy for some things. 
• Strange "https" issues: Looks like there are some bugs when logging in/out that cause you to get stuck on https versions of the site where links to posts don't work. The site claims to be logging errors on these so I assume it will get tracked down.
• Delayed Blogging! Looks like I can write 5 entries today and tell them to publish themselves at some point in the future by setting a date/time.  Now I can send posts... <doc brown from bttf>into the future!</dbfbttf>
• Insecure Content Warnings? When I log in and refresh my blog I get the "this page is trying to load insecure content" (or similar) warnings.  Now I have to click OK to that a lot. 
• Rate My Posts!  You can now rate blog posts!  I've already put in for a "highest rated" set of RSS feeds for the whole site and my own blog.  That would really help the human aggregation of the main feed.  IMO.
• Per post comment moderation: I can turn on or off comment moderation on the "per post" level. Don't know if I'll use it, but I can see the value.
• Only one trackback per post!  I noticed I was sending out a new trackback link every time I would update the content of a post. Fine if I linked to my own content, but frustrating when I linked to others and I couldn't remove my links.
• Post Previews! No more posting for real to verify the look of a post.

Thats it for now.  Thanks to Betsy and Telligent for all the hard work! Time to start tweaking my skins again.

Update 4/3 - After playing around a bit more

• Track Comments Via E-mail! As Scott points out you can now subscribe to our blogs Via e-mail if you want, but more importantly, you can now "Track This Post" if you are logged into the blog system.  This will let you get notified whenever someone posts a comment to the post you are tracking.  I know I'll make use of this to track conversations on other interesting blogs I may have participated in. No more manually remembering where you posted and to go back for the next week waiting for replies to read.  Each post also has an RSS feed for comments, but it would be nice to show the RSS button as an option for people who don't want to sign in or use e-mail to read blog comments. 
• URL Correction: Thanks for the correction. I had never noticed the friendly URL option in .Text.  I guess it goes back to the UI being much improved since I noticed now.
• Slight Moderation Hiccups: Apparently new posts don't inherit from the blog wide moderation settings. This means that I have to enable the correct moderation options on each post from what I can tell.
• Michael has a great post that explains some of the "3 inch differences" as well. He points out the blog keyword tagging feature is gone. I was using this to explain common MS used terms that everyone always had questions about like "PM" or "MSDN" or "SDET".  It would be great to get this feature back.  Michael had an even better use that I did by creating "tag like" links to MSDN topics on framework references.  
• Comment Posting UI: When I post a comment I no longer see the other comments in the thread... this is frustrating and I have to open a new window to gain context as I'm responding.  When I click comment it also reloads the page without moving IE down to the comment field. This caught me off-guard. I wonder if this is just my skin?
• Post rating might be more effective if anon users were allowed to rate the content... or we just come up with a ranking technique that takes click-throughs, comments, trackbacks, etc into account. 
• The admin UI used to have a quick link back to the home page of the blog you were editing. This was a nice shortcut to have.
• Quick Edits! The edit button is now below the post for blog admins.  This makes it MUCH easier to edit old posts. Previously you had to work a lot harder to find posts in the admin UI.
• "Logged in As" - It would be great to show a "Logged in as" in the title bar like the Community Server: Forums has. I'm pretty sure that Gret and I are going to end up accidentally impersonating the other from our home machines at this point.
• Spammer Redirects! Looks like spammers won't get the rank boost from links they leave since a redirect service has been added to the comments. URLs will all look like they are pointing to the http://blogs.msdn.com/utility/redirect.aspx page.  Unfortunately they can still leave URLs in the comment fields.