We sailed Prima for 12 days. Ship is beautiful, very upscale feel to it except Haven feels a bit minimalist. Lots of outdoor areas but weather wasn't the best for us. Haven outdoor without a roof so that is a waste if inclement weather.
Small venues my biggest complaint whether it be the clubs, Food Hall, or the Grill. However, if weather good, you could grab food and eat outside. Clubs I'd even suggest they were over capacity and a hazard.
Lots of outdoor areas, never felt claustrophobic and found it pretty easy to get around. Unlike BA which I don't like either, Prima seems to spread guests out much better.
The MDRs are fancy looking with the aft one great views.