Few things that we lost with the upgrade that I'd like to see come back:
The plain text editor function. This is hugely helpful when pasting article snippets to maintain spacing and alignment, and to strip some of the other formatting off the text you're bringing in. I used this nearly every time I posted an article and its absence is slowing down information I'm willing to bring to HuskerBoard because it's too much of a hassle.
Abbreviated Text. This was a fun feature that added a tongue-in-cheek quality to a lot of posts. This feature was in the drop-down menu that also contained tools for inserting a Member name, inserting code, etc. Some of that is available on the current post window, some isn't. Really, that whole menu had things I used - I'm just forgetting some of them now.
Editing without notice. Not sure what to call this, but it's a new feature on the board. It's useful to know if someone is changing their argument, but that really hasn't ever been an issue. This is a look-and-feel thing. It's ugly now, when you want to make a simple edit due to a typo or whatever. Case in point:
Multiple Quotes & Block Quotes. These both seem to have gone away with the upgrade, but both were hugely useful. Pretty sure you can allow as many multiple quotes in a chain as you want with settings in the off-the-shelf software. Being able to quote more than one response is sometimes necessary. We can set it to two or five or whatever. Nobody wants 20 nested quotes in a reply, but more than one would be good.
Board Rules link. It's helpful to have this available at the bottom of every page. At least at the bottom of every forum.
Member List. Unless I'm just missing the link, I'm not finding a place to see a bulk list of all members.
Search Function. Kinda connected to the member list, the search function sucks. You can get a list of members that way, but search flood control is enabled for any search action. For example, if you search members and get a list, and you want to sort it by join date, you can't if you don't wait 15 or 20 seconds after your initial search. If you don't wait, and click to sort, it tells you you have to wait X seconds and kicks you out of your search. It's crummy.
I had more, but not as much time to post this as I thought. I'll update later.