They actually did an amazing job for the amount of work there is.
ROA looks the same as always. They dammed it a ways back and put in some trees so from NOS it is business as usual just with no access to the island, Fantastic or the boats running.
The walkway behind Big Thunder and Fantasy Land is walled off nice enough that you would not know there was even a walkway there at one time. You can get glimpses of the work on Big Thunder but have not been on Splash in a while.
Long story short, don't let it deter you. There are MANY more walls up in late Jan/Feb than there are now!
Fantasmic is one of my ALL TIME favorites and long for its return, but I am thoroughly enjoying NOS at night time without the craziness of F! happening, It is actually a very nice change of pace.