We sailed Mariner in March, 2004 (Western) and then the Magic in September, 2004 (sort of the Eastern!) Even after four
DCL cruises, we still prefer DCL and booked two more cruises while onboard. With the savings you got, however, I don't blame you for trying a new ship! As long as you head out with the right attitude (don't expect TOO much...that was my mistake...I REALLY looked forward to trying the Mariner and I think I expected too much), I'm sure you'll enjoy a wonderful cruise!
IMHO, the Mariner is a beautiful ship. Area's superior to the Magic are the fitness center (it is HUGE!) and the outdoor sports court area. Also, there are two specialty restaurants (Portofino and Chops), which both offer wonderful service and delicious meals (the surcharge is $20pp...children 13 and older can join you.) We also enjoyed Johnny Rockets, although there is a surcharge for that, too. The ice show is not to be missed...make sure you get your tickets at the assigned area and time. And we enjoyed skating during our days at sea. There is a good sized casino, if you enjoy gambling and the Promenade shops are nice.
Again, IMHO, there are definately aspects of cruising that DCL does better. The evening entertainment (other than the ice show) onboard Mariner is not very good. Our local high school puts on much better productions. Also, be prepared to feel nickel and dimed. EVERYTHING has a charge. Also, they are VERY stingy with pool towels. Everyone gets one per day and the only way to exchange it is with your room host (no big deal, just an annoyance.) The staterooms are nice and well done, however they are TINY. We had connecting Atrium staterooms for our party of five and we were PACKED in. The bathroom shower's glass door, however, is a nice touch. The biggest difference, however, and the biggest surprise for me, are the evening meals. The dining room food and service is simply not very good. We are not gourmet types, but the food was really sub-par (our daughter was served bloody chicken two nights!) as compared to DCL. Think Perkins and that is the type and quality of the food. And desserts...very small servings and just not very tasty or imaginative. We ate at the specialty restaurants three nights (YUMMY) to avoid the dining room (which at $20 each starts to add up!) Also, fellow passengers tend to be either OLD (and a bit cranky if you have children or teens along!) or young party-types. We are a family with a teen and a toddler and we brought my mom along and we just sort of stuck out on Mariner (again, with
RCCL advertising, I thought we'd blend right in...just another surprise for me.)
To be clear, I am NOT trying to dissuade you from trying Mariner. Your post asks for responses and I just wanted to give you my honest scoop. Overall, we had a nice, smooth cruise on Mariner. Captain Thor does a great job keeping you informed and keeping the ship in good shape, the ports are nice and the crew is friendly. If you go informed (check out cruise critic) and with a positive attitude (and TRY not to compare it to DCL), you'll have a great trip. Hey, you'll be cruising the Caribbean.

How much better can life get?
