Hmmm, I wouldn't say it was a let down as such, but the set, cast and orchestra have all been drastically scaled down, and what little choreography there is looks clumsy. This does mean that you focus more on the actual book, score and performances (which is either a good or bad thing depending on how much you like the show

) The producer, Bill Kenwright, is not renowned for spending a lot of cash on his shows (but on the other hand, did take on risky shows like Festen and The Big Life etc) and whilst I don't mind 'cheap' revivals (Sweeney Todd & Sunday in the Park were amazing), Whistle just seemed less than the sum of it's parts
Don't go in with expectations of seeing anything to rival the original production, but if you like the show, I think you'll enjoy it - if nothing else, the two leads are great!
The most disappointing revival I've seen was Follies at the Royal Festival Hall - they had no budget and no rehearsal time, and the whole thing was embarrassingly amateur. Anyone else see an awful revivals?