Flew it a total of three times over November-December, LTN-EWR, and was really impressed. Twice was on a newer plane and once on an older one - the newer ones were obviously better but the old ones not too bad.
In many ways I prefer it to BA CW - the narrow body, single class experience beats being crammed 2-3-2 on a CW A380 any day of the week. Luton is easy to get to for me and the lounge has beer on tap which, whilst not quite free flowing fizz, is a pretty decent replacement.
Champagne on board is decent, food was good I thought, service was excellent - and the price was crazy compared to other J class tickets. Highly recommended on the basis of me experience, although I've yet to suffer a cancellation - not sure how you can run an airline and cancel flights so regularly!
Then again, LON-NYC business class only is a notoriously hard thing to get right (and profitable) - others have tried and failed...