Yes it is, we rode it twice last week. It is an awesome ride - very well done! We rode it once in the stand-by line, and once with fast pass. Have a great trip!
EXPEDITION EVEREST is still in SOFT OPENINGS so it may not be open when YOU are there. Lately it appears to be open most days - but there are no guarantees.
It is open but remember that it is still a soft opening. We got there early last week to ride it and found it closed until that afternoon (it opened at 11:20 A.M.). But on Sunday we arrived and were able to ride it 5 times.