Our family cruised to Bermuda on the Celebrity Summit in several cabins as part of a 50th Wedding Anniversary celebration. We couldn't have asked for a better ship or a better destination. Having read prior reviews warning of "worn" interiors and poor food quality, I was anxious about the trip (since it had been arranged months ago) - but there was nothing to worry about.
Yes, the ship is slightly older, and is scheduled for a "Solsticizing" complete renovation in January 2012 - but it is comfortable, extremely well-maintained and VERY clean. Sure, some of the soft case products (cabin carpet, chairs, etc) show minor signs of aging, but this did not detract from the overall luxury of the ship.
I like the Millennium class, since they're large enough to have a lot to do, but not overwhelming. They have a real "small ship" feel. The shows were top-notch, with an excellent comedian (Bruce Smirnoff) and an AMAZING violinist (Doug Cameron) who gave high-energy shows. The other musical offerings on the ship were excellent and varied as well - chamber music, guitar on the stern, etc. Very nice.
7099 - typical balcony cabin. Small, but comfortable. Slightly worn carpet, but everything else in good condition. Bathroom clean and functional. Balcony small, but serviceable.