Haven't been on Celebrity so I can't comment on that ship but I have been on Serenade and sister ships Brilliance and Jewel.
The cabins are beautiful on those ships (including Radiance). The announcements are brief and don't really factor into any pleasures of cruising to me.
The ship went to Hubbard glacier this past summer and probably alternates every other year to keep things fresh.
My understanding is that the food is superb on Celebrity but again, I can only vouch for Serenade and the food was outstanding.
The entertainment was also very good, although, it changes drastically from week to week. Thus, you don't know the caliber until you go to the performances.
Serenade has a putt putt course which is a lot of fun. The music is always
very good as is the Explorer Academy's dancers.
Hope some of this helps you.