Yes, I'm running one of the Ultra versions of 1.5.1 Optifine on it no problem. Also, for those having freezes, try not using MagicLauncher. When I used the old launcher (not the dev) to play Aether II, all of my memory leak/game freeze woes were gone! I assume it has something to do with how MagicLauncher uses the memory you allocate.
Also, how broken are dungeons right now? None of the chests have "real" items (they disappear, can't be equipped, et cetera). It's quite frustrating, but understandable at alpha stage one. Also, I've destroyed all five minibosses only to have the door tell me I need 0 or -5 more keys to enter... P:
"Our goal is to rework the Aether to be the best experience it can be in a multiplayer context and to improve on where we fell short previously. In addition to adding a new dimension, the Aether adds a number of different features, items, mobs, music, dungeons and blocks. As is, this is the first Alpha release for this version of the Aether, and it is for Minecraft1.5.1. I repeat, it is for 1.5.1. We haven’t added all the features we want to yet, but we will definitely be working on more content updates in the future"
I don't know... maybe
Minecraft has stopped running because it encountered a problem; Exception in server tick loop
A full error report has been saved to C:\Users\Bryan's\AppData\Roaming\.minecraft\crash-reports\crash-2013-06-12_01.58.37-server.txt - Please include a copy of that file (Not this screen!) if you report this crash to anyone; without it, they will not be able to help fix the crash
It works well with other mods for the most part, besides the interface ones like Inventory Tweaks. The new inventory modified by Aether won't let you use the mouse button to auto sort items. However, if you're in other interfaces like a furnace or crafting bench it'll work correctly.