The very first thing I did when logging back in for the first time in months was search the settings for a way to turn this new UI off. It's nowhere near as information dense as the previous version of the site, and I'm genuinely considering using custom CSS to just gut the site and fix it myself. This could be good, but please for the love of god let us toggle different sections on and off. I don't care what category the mod item is from, I don't care who made it, and I don't care when it was last updated. Those should be shown when I hover over an item, not constantly taking up space in the item's spot in the grid.
The item cards are so tall that on my 1440p monitor, I can fit at most 15 items on screen at once. I consider this a large waste of vertical space, and realistically horizontal as well since you could fit another two columns before running out of space. I come to the site to search for mods by title, and by thumbnail. The ability to turn off everything else would save a significant amount of space, allowing me to use the site better than I used to, since the left sidebar does look like it's a better option than the old UI. As it stands, I utterly despise the new layout, and feel like it's wasting my time just so that it can look nicer. Which it does, to be fair. The site looks much better visually, but again, my first reaction was "how can I turn this off?".
I don't mean to demean the work the UI guys have done, because they've clearly put a lot of work into it, but releasing it globally to everyone without an option to use the old UI is a missed chance. Your metrics can't measure what you aren't asking people. If you'd given them a chance to fall back to old.nexusmods or something, you'd get to literally see the ratio of active users who prefer the new UI, but without that you're just going to have to infer from complaints, and from active accounts becoming inactive, which is going to be difficult at best. Even something as simple as a popup along the top of the screen that asks outright "Do you like the new UI" with a thumbs up or a thumbs down would have been better than this.
However, to play devil's advocate, I went back to look at old screenshots, and I'm seeing a lot of the same things that I'm complaining about here. Sure, they were more information dense, but the old site actually has a lot of the same problems that the new one does. Perhaps we've all just accepted the old site's problems because we've been using it for a decade. The old site still had heaps of empty space, though it did have much smaller gaps between everything. I do somewhat miss the fade that the description used to have, where it would fade out closer to the cutoff point, to show whether there was more to the description or not. In fact, the old site might actually be worse for information density.
Here's a list of the changes I made in order to get the site looking a lot nicer in my opinion. Keep in mind that I'm not saying this is the correct solution, it's just what I want out of the site. Giving us the option to customize everything ourselves is the best solution, because then the people who want the current new UI can just keep those settings, but people who want the site to be denser can just adjust it themselves. Perhaps in a "View Options" or "Grid Options" menu whenever the grid is visible?
In .mods-grid: set both column-gap and row-gap to 0.5rem (they were 2rem and 2.5rem), and set grid-template-columns to repeat(auto-fill, minmax(14rem, 1fr)). (It was 16rem). This brought each card closer together while still leaving enough space to see the gap between them. It also shrunk the cards globally so that more could fit, without compromising the font size by globally zooming the page.
I disabled max-width in .next-container-fluid. I then disabled the creator, updated, and category elements. This brought the height of each card down to something a little more acceptable. Ideally, I would want that information to show up if I hover over the item, as I do like having that information available. Unfortunately, they just took far too much space vertically to justify keeping them. This won't be everyone's perfect layout, but it is a lot closer to mine. Disabling the max-width allows me to actually use the space that my monitor provides, which I understand the old site didn't have either, but it's incredibly nice to have it as an option.
A small flyout with that information (and potentially more), could be amazing. You could have the thumbnail cycle between the different screenshots provided for the file when hovering, as well as have a small flyout on the left or right side that shows a longer description, the release / update time, and the mod author. Ideally, if the mod author could be put in the lower right of the card where the downloads and likes are shown, that could work beautifully to keep that shown without a flyout. These changes meant that I could now fit 36 tiles on a single page at once, which is a massive improvement. The ability to change the sizes and spacing yourself, along with toggling what bits of information are shown, could achieve this effect or better. I wanted to also figure out a way of capping the description to only 3 lines as opposed to the 4/5 it currently has, but couldn't find where the height was set. I did find a min-height value, but changing it seemed to do nothing.
I've attached images with a before and an after as an example. It's perhaps a little too far, but it's readable and functional. perhaps most importantly, the after version is the kind of format that I can use to quickly browse for the mods that I want. The ideal solution is to give us options and sliders so that we can adjust these variables ourselves and save them to our account or even just local storage.
I feel like the new site could grow on me, with more customization added. It certainly has potential, but I don't think it's there yet.