To be fair right from the start, there is nothing wrong with the ship itself - it seems well kept and clean - decks areas are well maintained and bright and clean, public areas are well decorated, clean bright, and pleasant, and the cabins (ours at least) are clean and well maintained (see first point below however).
The itinerary also was well chosen and enjoyable - all our trips were extremely enjoyable, seemed well organised, and were not outrageously expensive.
So whats the problem(s)? A number of points which cumulatively completely ruined our cruise, as follows ;-
1. BEDS. The mattresses on our beds were so ridiculously hard that a nights sleep of any sort was next to impossible - we prefer a firm mattress, but these were police cell grad or worse. Each morning we rose feeling dor tired and with aches all over our bodies - this itself was enough to make the cruise miserable.
2. FOOD. Without going into great detail the food was very poor and clearly down to a price - more like school canteen standard (and that's being kind). To make this worse the staff seemed to think that we were all in an eating race - each finished plate was whipped away as the last fork-full was in the mouth, and the next course was there (we were on the second sitting so there was no need for this). We've never eaten a meal so quickly, and asking then to slow down just meant that your food stood in the holding area for longer and thus arrived colder (apart from the ice cream which arrive melted).
A complaint about the food produced the restaurant manager who (unusually) had a good command of English and mouthed apologies and soothing assurances of better to come - however nothing changed proving that he had no authority to make changes, no ability to do so,or no desire to do so (all all three).
Evidence of this was that as the week progressed it got increasingly difficult to obtain a table in the alternative buffet restaurant as more and more guests seemed to be attempting to escape the main restaurant. Just why they have formal nights escapes me, as this presupposes that dinner is an experience to look forward to, rather than to be tolerated as an unfortunate necessity for life. My wife summed it up beautifully - "the first holiday that I've ever had and not put on weight".
3. STAFF. Whilst the deck staff are in the main pleasant with a reasonable command of English, the same cannot be said of the restaurant and bar staff (with a few notable exceptions). They are unhelpful, sometimes to the point of rudeness, with a very basic knowledge of our language, and when asked for anything or questioned, quite aggressive in their refusal.
At breakfast and lunch (open sittings) we were not asked or invited to sit at a particular table - we were told to - yes really ! A request for an alternative table was either completely ignored or bluntly refused.
The only way to communicate with the staff would seem that the guests should have a good knowledge of Russian, Estonian, Latvian, and Polish. Did I just say "guests"? Not sure if anyone's ever told them that that's what we are.
4. DRINKS. The wine list is ludicrously over-priced (you can drink cheaper on Cunard) - I resent being asked to pay these prices for quite mediocre wines. as an example the cheapest bottle of wine on the list is the house red, which is a really quite poor wine at the unbelievable price of £14-90p !
A glass of wine in the bars which was listed on the price list as "25cl" tended to vary in amount according to who was serving it, and always less than that as far as we could see.
TO SUM UP. The whole ship seems to be run for the convenience of the cruise line and the staff, rather than for the convenience of the paying guests.
OUR RECOMMENDATION. If you are looking for a cheap cruise, forget Marco Polo - go instead for Fred Olsen (preferably Balmoral) - they are not much more expensive but the staff are helpful and understand English, the food's good and served properly, the drinks are very reasonably priced, and you can get a good nights sleep.