Initially, I missed the page numbers. I have to use Postcrossing on different computers, and the page numbers helped me to roughly get back to the place where I stopped reading. If I had time, I took links with the exact posting number, there is a link at the top of every post in the old forum that gives you the direct link to the posting. The new forum has the same feature: In the top right corner of each posting is the time since the post was made, it’s a link to this post. Unfortunately I have noticed that on all my computers (always using the latest Firefox, currently 82.0.3, on Windows) the links in the new forum do ot work accurately (I often end up off by several posts, sometimes too old, sometimes too new), while on the old forum this worked perfectly.
I also work with browser sessions, meaning my most used topics are always opened automatically. There, again, the new forum has issues restoring the tab to the correct place in the thread, while the old forum did that very precisely.
One nice thing I noticed is that while scrolling, the URL in the browser’s address bar changes as you scroll to always show the direct post link to what you are watching. This post number is the last part of the URL, e.g. here I right now see 11591/5, the 5 is the post number. That makes it very easy to create a batch of bookmaks of all my open tabs with info where I am in all the topics to carry over to the next computer I need to use. Now that is a very useful feature for me! In the old forum I would only get tabs with the topics at the first post of a page. Unfortunately, as said above, the display accuracy of these post links is not very good, but still better than just getting to the start of the correct page.