How exciting! The Monarch is currently the oldest ship in the Royal Caribbean fleet and will be transferred to Pullmantur cruises in Spain next April. At one time she shared the title of largest cruise ship in the world but is now considered small. Time marches on.
The Monarch (and sister ship Majesty Of The Seas) have a loyal following and the ship offers a great value and introduction to cruising.
Some things to note: the standard outside and inside cabins are very small at ~119 square feet. Is this the category cabin you have? Despite the small size they are very well laid out and fine for a short cruise. However if you have more than two people in the cabin you will need to coordinate your shower/dressing times.
Monarch has a sushi bar that is great. It does carry an ala carte fee but it is worth it.
When is your cruise?