I don't mind moving the IAD logo and menus to the top of the page (this would improve compatibility with lower screen resolutions anyway), but as for the forum design/style: if you are able to restore the old style, please, please, do so. As primarily a desktop user, the new style is awful. It is typical of run-of-the-mill, abusive "modern" web design, being designed specifically with mobile devices in mind (and flipping the bird at those of us using traditional computers), and displaying the detestable influence of typical "modern" styling.
As is typical, it wastes considerable amounts of screen space, hiding information and functions that was formerly displayed directly away in menus or tooltips (which simply diminishes usability in a desktop environment), and assuming users who use an OS DPI setting of, say, the traditional 96 DPI really meant to select 120 DPI or more instead (the font sizes on thread pages and reply forms aren't so bad, but those on forum index pages are ridiculous). Guess what? If I have it set to 96 DPI, that's what I want. The font sizes should be determined by the DPI setting only, rather than assuming that someone's DPI setting is unreasonably low for their physical screen size and compensating with an unreasonably high point size. Similarly, the layout should not assume that a 1024- or 1280-pixel-wide screen is a mobile device. If someone's mobile device (or computer with a high-resolution monitor, for that matter) reports an unreasonably low DPI setting for its screen size, that's not others' problem.
The icons are typical examples of flat-ass "modern" design, which sacrifices usability for the sake of being "sleek" and "modern". Shading and colors help delineate different parts of images and UIs, but the trend these days is to deliberately eschew this for the sake of being "modern". They are also implemented as font characters, and render poorly on desktop screens with traditional DPI settings, even with sub-pixel antialiasing enabled. Supporting "emoji" only instead of traditional image-based smileys is another fail, as "emoji", being Unicode characters, suffer from the same poor rendering as the icons. I'm not against allowing "emoji" to be used, but they should not replace traditional smileys.
At least the new forum doesn't seem to be as slow as a snail in molasses, as is all too typical with "modern" websites (due to lazy-ass developers using as much JavaScript, and especially JavaScript frameworks, as possible, lest they have to spend the time to actually write good, efficient code and use better-performing simple HTML and CSS where possible).
In summary, the new style would be acceptable as a user-selectable "mobile" style, but it should not be the only option. The old style was overall very good, providing mostly great usability in a desktop environment, while also providing a decent mobile version used by default on mobile browsers. I'm in favor of a site being reasonably usable on a mobile device, but it should not come at the expense of usability on a computer. As someone who uses a smartphone to browse from time to time, I have no reservation saying that smartphones provide an objectively inferior experience for browsing and especially typing. Those who ignorantly think that "hunting and pecking" on a virtual "keyboard" and holding their arms up to tap and "swipe" their fat greasy fingers on a touchscreen is somehow an advancement over using a real keyboard and precise pointing device should *not* be catered to; if one or the other device has to suffer concessions, it should be the mobile device.