I say "first timer" because I don't really remember my first cruise as a teenager - except being REALLY sick. Hence, I had NO desire to cruise again, but my husband surprised me with an anniversary/birthday/valentine's day cruise. I was assured the newer ships are much better and more stable and he booked a balcony close to mid-ship. For safe measure, I wore accupuncture wrist bands. Either I didn't need them, or they were magic. I didn't give being sick a second thought and truly enjoyed the cruise.
The Jewel is a beautiful ship, more on the "elegant" side than the "party" side in terms of decor. All the glass around the Centrum and various public spaces helped eliminate any claustrophobic tendancies I may have had. Our room was compressed, of course, but roomy enough and I loved all the hidden little storage areas. Our steward had no problem keeping our ice replenished and who doesn't love towel animals? There was a good mix of lounges for different tastes. I like that it wasn't one of the jumbo ships, as it seemed more manageable to get from point a to point b and I don't think I would have wanted even more people around. Although there were over 2000 passangers, I don't think I ever felt over-crowded, except in Grand Cayman waiting for the tender to shore. I would say the shows were entertaining, but not the broadway caliber they are hyped to be. I didn't expect them to be, though, so that was not a disappointment. I would highly recommend catching the "Love & Marriage" game show. It was hysterical. Of course, that would depend on the participants and host, but Dennis the cruise director on our cruise made it laugh-out-loud funny! We upgraded to the Italian Restaurant one night (Portofino) and it was delicious and worth it. The food in the main dining room was good, as well. Not amazing, but better than what you usually get for mass produced meals, and more than plentiful as you can order as many apps, entress, or desserts as you like. It is a great chance to try something you may have been wanting to try but haven't wanted to pay for in case you don't like it. I think the buffet food at the Windjammer was just OK, but lots of options. We loved that they monitor the lounge chairs at the pool so that if someone is holding a seat and hasn't shown up for 30 minutes they clear it for someone else. It made it easier to be able to get a chair.
There were not a lot of children (which was nice, since we left ours home), but it was very family friendly and I would definitely think about taking my kids on an RC cruise if we didn't want to spend extra for Disney. As one family pointed out, their kids could ride the slide over and over, while on Disney they would probably have to wait in line with tons of others. (I may be swayed by the "when you wish upon a star" horn they have, though!)