Hellshade what are the new features, changes in UE ?
It's not my place to steal the devs thunder with specifics, but I will say this:
The French aren't just getting two new planes and they are done. They are going to be integrated into the war better than ever before.
The airfields have received a lot of attention to detail. Not just new airfields as Louvert pointed out and more than just the layouts of existing ones, but in some cases what types of planes you'll see deployed there and how things change over time. Some important airfields will be easily distinguishable from the rest. Coming home after a long mission - day or night - will be more gratifying. Overall, the airfields have been brought to life and it's hard to imagine just how much this adds to the immersion of WOFF UE over 3. Even the feel of landing at one has been revamped depending on varying conditions. You will probably never want to use 'Air Start' option again unless you are really pressed for time.
Installation has been streamlined and improved. I'm sure the devs will layout the details when it gets closer to release. - No, I have no idea when that will be.
There are new options in the Workshop. Some will help folks with more modest GPUs in certain conditions while others extend the functionality beyond just what is programmed into WOFF Ultimate Edition itself. It's up to the devs to let you know what that is.
Some sounds have been greatly improved, including the Allies Vickers machine gun which is much more satisfying to fire. I could never go back to the older sound after flying UE.
Just when I thought development for WOFF was winding down and coming to the end of it's life, the devs have decided not just to give it an extension but really a sort of re-birth. It's all very much an unexpected gift.