Well, having tried it out after being aprehensive about the changes, I'm okay with it but have a few suggestions/comments/questions for improvements:
1. The tag display needs a little work. The icons need more visual variety. More importantly, I think there needs to be text in the tag field or post title that spells out the tag choice. In a perfect world, the tag names would also be written out as "D&D 3e" instead of "DND3E"
2. The tag browsing could use some help. I understand that a checkbox-style interface probably isn't available right now due to software limitations, but I still really want one. As an alternative, I would like to suggest a sticky thread that lists all the tags and has links to them. This would help in two ways: First, it could provide a handy list of all tags and explanations for when to use them (for example, when to use the WoTC tag instead of DND3E or ALLDND). *Second, it solves a hunting problem. Right now, you have to find a post with an appropriate tag to sort by that tag. I imagine this will be a real pain with some of the rarer tags.
3. I still want D&D Next to be in it's own forum. It's not an issue now, but I really think that it will dominate whenever there are major announcements. This is also the only reason I want the checkbox tag interface, so it would solve that problem, too.
4. Why does Conversions still have it's own subforum? Given that Next doesn't have it's own, this one is hard to understand. Couldn't we just have a Conversions tag?
5. I think there needs to be a way to edit tags. I went back to an old thread I started, and couldn't find a way to add one. I think this will be a PITA if people forget to enter a tag when they start a thread.
Just my two cents.
*Edit: just found the "Prefix" drop down under "Display options". This solves the hunting problem but it's relatively well hidden.