Agh, one more post about this. Another feature lost, as a pp mentioned upthread, are the useful colour changes - not just on the highlight posts feature (which we used to be able to customer in different colours?), but also to distinguish user posts from sticky posts at the top of a board, and the colour change to tell you you've read a thread.
The visual impact of the old boards was really simple and you could see lots of thread titles at once, see which ones you'd already read from the colour change, scroll down quickly, and so on. Now it's cluttered and you only see a few thread titles - lots more scrolling down and it loses the visual impact of seeing what felt like much of the whole board at once.
Like someone else in the thread, I used TIO and TIW as a quick shortcut to jump between my most popular boards because of you click directly on the main "Chat", "AIBU" links etc. Another useful navigation feature that's been removed.
I've tried again with the site this morning to see if I can get used to it and I really can't. The functionality is slower and more cumbersome. It's like wading through treacle where it used to be easy and fast. Two clicks to move to top and the slower scrolling motion - really annoying. No ability to jump directly back to new posts on TIO - lots of time wasted scrolling. No page jump bar at top - ditto. I feel like I can only see half the site, it's a much slower and more tedious experience, and the rewards of seeing what people have posted on a thread are outweighed by all the repeated scrolling and tapping. I really don't like the user experience at all - it feels very old-fashioned.
The only bits of new functionality as far as I can see are the smilies, and the "Go to page" option - which isn't even working! Why lose so much of the basic functionality just to add these?
I can only think that the MNHQ team only tend to use the desktop site and so aren't accustomed to using only or mostly the mobile site, and so don't notice the changes in the user experience, or think they're not important because the mobile site is just a lesser version of the desktop format. But for those of us who use MN exclusively on the mobile site and when out and about, this really does ruin the whole user experience. I can't state this strongly enough 
This isn't like "one of those times when Facebook changes and everyone forgets about it in a few days", because even Facebook normally takes care to preserve the same level of functionality even if it switches it about or does a cosmetic redesign. As I posted above, it really is going backwards if you take functionality that used to be one step (one tap, easy and intuitive) and introduce another step (two taps into a drop-down) to do exactly the same thing. It might not matter as much if it's a little used feature. But something like the top button on posts and the top page jump bar were used routinely on every page by a lot more posters than I suspect MN thought. Hence my suspicions that HQ aren't heavy mobile site users themselves or they would immediately have noticed how heavy and cumbersome the new site feels without these features.
I know this is another long post but I really do think this will make me give up MN. Part of the addictive quality was how sheer bloody fast it was to navigate the old mobile site - on the bus, baby in jumperoo, waiting in a shop queue - quick couple of taps and you could keep abreast of TIO updates and scan the boards for something interesting. Now all the scrolling, extra tapping etc. makes it much less enticing. From being a pleasure it now feels like a real chore. I don't use the desktop site (for a variety of reasons including RSI, no laptop etc.) so I'm unlikely to keep on here if the mobile site stays like this.
Really, MN - please accept that this is a much worse version of the mobile site and people's upset about it really isn't going to be fixed by a few technical updates and a cheery "you'll get used to it" message. Sometimes things really are got wrong, and this is one of them.