There is always a problem when staying within the boundaries of a pedestrian zone.  These mainly centre around late night and early morning noises and disturbances.  These can be late night noisy drinkers, street cleaning and rubbish removal, paricularly glass.   This can be experienced  in Nice, however, the problem was much worse in Montpellier.

Apart from the normal street cleaning and rubbish collection parts of the pedestrian areas suffer from late night bars patronised by large numbers of students.  Some bars stay open until 2-3am and drunken students can be roaming around singing, shouting and kicking bottles until 4am.  Two hours later the rubbish collection and street cleaning starts, which is certainly needed when you see the rubbish that has been left behind in the narrow streets. 

If you are staying in one of the hotels it shouldn't be too much of a problem as most of the hotels are situated just outside the pedestrial zone.