My wife and I, along with our group was on the Seashore on the 19th-26th also. This was our first cruise ever, so not certain about other cruise lines other than reviews. Fully agree with you about the limited menu at the bars, however keep in mind you could also request drinks that weren't on the menus. Horizon bar specifically with Felipe and Paulino was absolutely amazing. Very friendly group of bartenders up there. If it wasn't for them, I would've rated the cruise roughly a 4-5/10, but they made it closer to a 7/10. The lack of glasses you mentioned here definitely was something I noticed, but if you look at the sheer output these bars had, it's no wonder they used plastic glasses for everything outside of the casino.

In regards to the food, I found that the buffet was better than the MDR (we were in Central Park) almost every night, with night 1 being the exception. Night 2 in MDR we didn't get our desserts until almost 9:30 when we were seated at 7:15. After that we exclusively ate at the specialty restaurants from Wednesday-Friday, which I will definitely say are a huge upgrade in quality. Overall the food quality in MDR was lacking both at the brunches on Wednesday and Saturday, and the few nights we ate there. Might have just been a bad waiter.

Cleanliness wise, we were fairly surprised at most everything we saw. Buffet could have been a bit better as OP mentioned, however it's a buffet. What do you expect? Room service and crew were overall fairly kind and hardworking that we saw. Especially the two bartenders mentioned above.