I think the new one is definitely prettier, and I like the flanking on the hallway to the throne. I personally never had any FPS problems on the old dotf but if other people did then that's a valid issue. I like how there's more open space in a number of areas, namely throne. I like the smaller, curvier catwalks in gen.
I dislike the changes to side in general and the removal of catwalks.
Simply put, the rebs can flank more quickly and easily now. Firstly, the hallway from Imp spawn to gen either seems longer (?) or the time before the gen door opens seems shortened (?). Even if I spawn right by the side door and book it there immediately I always leave the side door just as the rebs' door opens. This makes "defending side" really a moot point. The rebs, from the layout and the timing, have the advantage when it comes to defending side. Mostly what I've seen happen is that the imps will get held up outside of the door as one person goes and does the hacking; either the Imps will then shitstomp through the rebs and run into hangar or the Imps will get their shit pushed in and rebs will cruise on over to T junc and flank. The imps actually preventing the rebs from hacking seems very rare to me. I feel like this sets the Imps up for a loss most of the time because of how easy it makes hacking side, flanking, and utterly decimating the T-junc defenders. Because throne can't be held except by sheer numbers (which can't be done except from the outset because main defenders will get crushed by flankers and because side defenders can't get to throne before rebs can) the Imperial options to defend seem limited.
I'm not complaining about the ability to flank but the ease of it. The distance from hangar to pit combined with Imps always getting into gen before rebs in the previous dotf gave the Imps a valuable tool in that they could use attrition to hold off the rebs. A smaller Imperial force could hold off a large Rebel force simply by being a pain in the ass and positioning itself throughout the generator. They'd have a headstart on getting into gen so they could actually position themselves throughout it. Additionally, even if you didn't actually keep the rebs from successfully hacking, you would be enough of a speed bump that main could either be cleaned up or the defenders in T junc could fall back. As I said before, this leads to Rebs being able to flank more quickly and more easily now.
The ONLY people who go into the gen catwalks now are Mandos looking to snipe and Jedi looking to hunt the Mandos down to get kills. There is no reason to actually go into gen proper, especially because the Imperials cannot get into the generator before the rebels in any real capacity; gen combat is limited to the entry T and the hacking platform with only HONORABLE DUELS occasionally straying out before someone gets sniped. Fights in gen were some of my favorite parts about dotf because of the truly 3D nature of the combat. No, the game isn't 2D or isometric, but most combat is you moving along a flat plane: Gen and the hangar/imp spawn catwalk gave people a versatile tool that was, simply put, a fuckton of fun.
The decision to make throne a King of the Hill rather than Hack the Terminal is a moot one; I don't have a strong opinion of either. However, I dislike the ease with which Rebs can simply cruise through with little to no resistance from the Imps. Throne being a brutal oppressive chokepoint that could only be accessed by siege was part of what made it fun. I completely see WHY it was chosen to make that change (because when it wasn't fun it was terrible), but I disagree about the manner it went about. I like that rebs can fight in a throne that is completely open, but I also dislike the Imps' inability to defend it (both due to their inability to really defend side AND throne, and due to how quickly the rebs can just flood throne).
From reading your posts, Mace, and the dev diary you posted, I get the feeling (and I could be wrong here) that a number of changes were made to get rid of the things that, much like throne sieges, were terrible and oppressive to a number of people when they didn't work... yet were fun and memorable to a number of people when they did work. I don't disagree with smoothing out kinks and bumps, but sometimes those kinks and bumps should remain because they're what makes things fun. A simple, streamlined and efficient map is... Boring. There should be struggles and fuckups and places in the map that are pains in the ass because that's what makes the game fun. I feel there should be places in a map where things aren't guaranteed to go your way because those places are often where the fun is had. Overcoming the kinks and bumps, as a player, or using them to your advantage, is part of the fun. Yeah, rebs can easily hack now and that makes things easy and streamlined for them... But I don't have fun or feel a sense of accomplishment (Or even that I'm really aiding my team) when I hack now.
If I were able to wiggle my magic nerd wand and change dotf, I would bring back catwalk, bring back pit (I like the curvier, slimmer gen catwalks in gen proper, I'd keep those), and change how access to throne is done. The attached image shows the idea. Pit as before is brought back; the first two terminals open the blue doors allowing the rebs easier movement and the final terminal opens the green doors. Throne has three doors to it, allowing both for rebs to invade an open space and for imps to actually defend it; the doors should have less health than old dotf throne door did, maybe half as much. Doors with the red Xs can have their terminals destroyed to open them. Thus, rebs can either go for a full side hack and have throne completely fucking open, or they can rush main and have a prolonged siege; if they're smart they'll take their time and blast open all five doors... Or maybe they're dumb as bricks and just run in a straight line towards the deka.