First of all can I say that Cunard did give us a very reasonable upgrade from a guarantee D8 cabin and the actual price was very good including NY for New years Eve:
We had been on the QE in April last year and found the ship quite classy although it did have problems. We had been promised by people on that that QM2 was vastly superior and we looked forward it.
QM2 is probably the most attractive of the large ships. I personally find the decor not to my taste. The refurb had taken place but it made us wonder how bad it was before as bits of still looked a bit shabby; the restaurant and the theatre were bland and uninspiring. QE had a nicer restaurant and theatre (with boxes etc).
The food was ok but did notice quality and portions was lower than even last April on QE. Staff were fine and we loved the Planetarium shows (went to all of them). Met some nice people.
Nice room. Very quiet.
In conclusion: I think that this being a winter transatlantic crossing skewed my opinions as Im not used to being inside for so long and if this had been a summer med cruise my review would have been more positive. I would probably go on QM2 again but not transatlantic (unless really good deal!)