I get that this is a very rough development version right now, but some thoughts:
It's important to delineate sticky topics and also locked topics. Both of these look near-identical to normal topics in the current implementation, which makes navigation a lot trickier and annoying. This is especially the case for sticky topics, because usually it's easy to gloss over them to see the newest topics, whereas now you have to do a bit of brain work and/or strain your eyes at the icon to figure out where the sticky topics end and the newest topics begin (or, if you're Red Mones, they have disappeared entirely
).
Being able to jump to any page of a topic directly from the subforum view is a super convenient feature, standard to most forums, and one which I think would be a bit silly to throw away.
On the subforum view, where you're more likely to be looking at topics going back months or years, it seems much more intuitive to have absolute dates than time elapsed. Knowing that a post happened 1789 days ago is far less useful information than knowing that it happened on 7 January 2016.
I'm a bit concerned about usability on larger monitors; that said, for my own monitor, the addition of the sidebar seems to have resolved the initial concerns I had about this (but that's just my own case).
On the other hand, I'm somewhat doubtful that the sidebars would serve much functional use beyond squishing the topic view to make it more readable. It feels a bit awkward to have that tiny bit of sidebar followed by so much empty space. I'm personally glad to see the forum descriptions make their return via these sidebars, but considering that they were removed for being redundant, cluttering, and not that useful, I'm a bit confused as to why you'd then reverse that and add it back. (EDIT: went back to the forum redesign topic, I see your thoughts on that now. I guess my thought is if the descriptions were never that useful [though that is a premise that I don't really agree with], then adding
more of it doesn't seem like it would help matters. I'm also not sure what a longer description would do that can't be done via stickied topic. Especially since that adds a new website component that needs to be maintained [possibly hardcoded] by you, in which case I would be concerned about it going out of date or being underutilized/unused, much as the old forum descriptions were.)
Finally, this one is a bit less important, but nonetheless, topic icons are still something that people use that adds character (and occasionally, information, eg Daws' use on recent UH topics) so I'm not sure how I feel about those being removed.
Also, weird idea, but maybe it might be cool to incorporate people's avatars into the post views, like is done on the front page. (I'm probably going to regret saying this because I very much am likely to not like how that looks...
) Same with the time icon (but for that one I do how like that looks
).
Unlike some other people who mostly use the Recent Topics page to browse the forums, my workflow involves going through each subforum and viewing the topics there. So this is a pretty drastic change, and I suppose these are my accompanying thoughts.