There are a few differences between CL and a standard room. First, all CL rooms are located in Hawaii (with the exception of the suites). The building is secured and guests need their keycard to enter.
There is a lounge on the lagoon side of Hawaii on the second/third floors. There is a large, wall-height window in the lounge overlooking the lagoon and castle (there are pictures on the first page of the thread
http://www.disboards.com/showpost.php?p=43769556&postcount=10 ) In the evening you can enjoy Wishes in the lounge and the soundtrack is piped in.
There is food service offered in the lounge and this is included in the cost of the room. In the morning there is a light breakfast with coffee/juice/tea, fruit, baked goods and oatmeal. During the day there are snacks such as fruit, cookies, crackers etc. There is always soda on hand and you can ask a CM for beer. You can take food/beverages from the lounge back to your room or to the pool/beach area. At dinner time there is an h'orderves type menu offered, with finger foods, crackers & cheese, etc. Later in the evening desserts, liqueurs, beer and alcoholic punch are served. You can find a link to the menu on the first page of this thread.
Another "perk" of CL is the use of the Poly's IPO office (Itinerary Planning Office). They can book ADR's and recreational activities for you.
It's really a matter of opinion as to whether the extra money is worth it for you. Our family likes having the extra space of the lounge to get out of the room. We are also pretty light eaters, so the food offerings work well for us (with our big meal of the day at lunch time). If you are big eaters the food in the lounge will not be a good meal substitute for you.
Hope this helps!