I think you will have fun. We went on our first cruise last summer and loved it!
However...I think that if you want to avoid the crowds, a little research can help you out, just like at WDW. For example, before we cruised I read over and over on the DIS boards about how crowded the pools are on sea days and you have to get there early to avoid the crowds. We utilized the pools around 9- 11 a.m. on our sea day and didn't think it was bad at all! Also, in the evenings the pools were practically empty. Same with the afternoon of our Nassau day. I also read that if you get to dinner even 5 minutes early, there is a huge crowd of people. So we waited to walk to dinner until just a few minutes after the dining room opened, the last of the crowd was just being seated and we had no wait.
Go to Shutters early on your last day.
I"m sure there are more tips, but those are the biggest ones I"m glad I knew. We were on the Dream when it was sold out, and I never felt like I was in a crowd.
We never had time to do some of the cool stuff on the Dream, like the Midship Detective Agency.