I'll second
@blackb0x 's concerns.
Keeping the tags + subforums seems to me to be better usability.
In its current form, with my own personal browsing habits, the site is pretty difficult to just casually browse.
The auto assigning of tags is a huge start, I know it has to be done this way, but some of the older threads will be much harder to find now. Translation threads in GBA is a good example. Only 3 gba projects show up when you click Translations? Many of those older threads will never be updated with new tags.
Another example is the Flashing Hardware GBA subforum, which was pretty much the dedicated EZ Flash subforum. My flashcart is an EZFlash. There is no way for me to single out posts that would have only shown up in that forum. Now if I select hardware, I'll get posts for various hardware and not just what I have. Of course this can be fixed with new tags. but I'm not sure if you want to go down that road of "tag management" every few months to add/remove tags from the pool.
My last example will be the Switch forum. It's really difficult to read through. Why is there 3 different tags for homebrew? (homebrew, homebrew app, homebrew game). There's no Q&A or Support tag. Although I see some Question tag and Discussion tag in other posts. It seems you cant pick these when making a thread? There also seems to be a number of threads that have no tags, will tags be made a requirement? Then on the other side of things, I can see issues with people adding tags that aren't even relevant.
Who knows, I might be in the minority with how I read the site. I usually read every thread and every post in a handful amount of sub forums. Even with the tag system, it seems I will be self filtering a lot as I scroll through the threads.
I'm also assuming with the currently upgrade, tapatalk support has now been dropped.
On the good side of things, the mobile version is VERY usable, and the performance of the site (page loading mostly) has increased noticeably.