2Fltravelers (see above) have written extensively about this cruise. They should be praised for their level of detail.
If you are expecting Crystal Cruises or Oceania or the Queen Mary 2, please book a different cruise. The Marguerite has everything that you could hope for in a small, river-going vessel. What--no big-named comedian or a stage show re-creation of "Phantom"? You'll be too exhausted at night to do anything but collapse into the pool (which is bigger than you'd expect for a ship of this size).
Sure--the food is made so that it doesn't upset anyone, so use the "action station" to try something new at lunch and don't be afraid of the little red chilis. For the most part, we stuck to fish, chicken and lots of vegetables and fruits--if you do, you'll be happy.