My wife and I (mid 30's) had a perfectly nice time on Seaside. The staff was friendly and engaging, although there was occasionally a language difficulty. The cabin had plenty of space for two people, although the bathroom was quite small.
Dining was perfectly fine. Buffet was average but convenient for breakfast/lunch. Dinner in the dining room was quite good, I had one entree the entire week which was not made well. The appetizers/desserts were all high quality. Dinner at Butchers Cut one night was very good. Venchi was outstanding.
Didn't have any crowding issues at the pools, yes they were busy, but we found places to sit at the Jungle and deck 16 pools every time we went. Bar service was slow, but I'm guessing it is because most of all of the frozen drinks on the menu which take a while to make. I don't speak Spanish, and I never had a problem being served in order.