It's not so much anything about the quality of the voices involved - years of smoking certainly were not kind to the pipes of Ian Anderson - but the technique of the singing. With Transatlantic's 70+ minute outing, while the voices don't sound bad, the phrasing and inflections leave much to be desired, lacking, for the most part, the confidence and impact heard from the very first track of TaaB 2. When the 1:37 mark of an old dinosaur's follow-up project is, vocally, stronger than the first fifteen minutes of a prog rock supergroup's intended magnum opus, someone hasn't done their job right.
I have, thus far, enjoyed The Whirlwind, but if what I've heard so far is any indication, I rather doubt that my reward for reaching the end will be anything like as powerful as the pairing of Confessional and Kismet in Suburbia. Anderson's vocal work on TaaB 2 may not come close to the original album, but it's still miles ahead of Transatlantic so far.
EDIT: I was going to cut this album so much more slack before they started padding the length with mindless repetition. I can only hear "Is it really happening" so many times before I conclude that you've run out of ideas.
EDIT 2: I was right. In summation, The Whirlwind is an instrumentally fun/kind of impressive album/song with merely okay lyrics and mediocre delivery of those lyrics.