We are Celebrity Elite with 14 cruises, early 60's and have also sailed P&O, Princess and RCI (and now Cunard). Our comparison is based on the Queen Elizabeth (a liner) vs the Eclipse (a cruise ship) which we have sailed 4 times with another cruise booked on her for August 2012. We did this short 5 nights 'taster' cruise with Cunard on 18th May to Amsterdam, Zeebruge (Bruges) and Le Havre. We did not have the best of the weather until the last day of the cruise when the sun shone gloriously.
Amsterdam was overnight, we had all been before so just walked around soaking up the atmosphere and admiring the 'views'. As the Pursers Desk did not keep its promise of showing the Champions League Final we found a pub alongside one of the canals ashore that was showing it and returned there in the evening. Zeebruge, we took the free shuttle bus (Celebrity would have charged!) to Blankenberge and then caught the train (Euro 5.80 return) to Bruges. This was a beautiful city and we thoroughly enjoyed our day out. Le Havre, we had a ship's tour booked to the Normandy beaches and war cemetery which was cancelled, unbeknown to us -- a very upsetting state of affairs (more below) and one which has obviously affected how we feel about cruising with Cunard in the future.
The following is just our opinion and our experiences, others will have their own opinions and will have had a totally different experience, we all see the world through our own eyes, even on the same cruise ship.
CABIN 6050 - quiet position, good room steward. Very, very small bathroom with awful shower curtain. Cunard allow smoking on the balcony which is something I don't like at all.