When starting a new thread, it looks like the default is now HTML. It would be helpful if groups would remember your preferences for that group. I also try to open "Post" in a new window so as to not lose where I'm at in Message View.
I've been reading Beta from the web page. I find it's easy to jump between Message View and Expanded Message View. There are a couple things I would offer as suggestions, and I'm not sure if some of these might not already be on your to do list.
1) Reading with the newest at the top, I have to continually scroll down to find the message number I'm on. The message number might be more useful at the top of the message.
2) When trying to go back to where I left off, I have to scroll down to the bottom of the page to go back a page, and if I need to go back more than one page, I have to scroll down again. Can the page selection box be at both the top and the bottom of the page?
3) When I start a thread as the group owner, it shows up as coming from my own member identity instead of as coming from the group owner. There are times I really do need make it very plain to readers that I've put on the Group Owner hat and it's something serious. Very seldom do these need to be Special Notices.
As I noted, these may already be on the list.