Visiting Disney early in the year may mean less crowds and better deals on packages and flights, but there is a downside.
During the early part of the year there are more ride closings for rehabs and refurbishments. In addition, some of the resorts use this down time to spruce up their pools.
It's always a good idea to check for rehabs and closings when planning your trip so you can see how it will affect you.(for the most up-to-date rehab listings for parks and resorts, visit: www.wdwinfo.com/wdwinfo/rehab.htm)
While specific rides might not matter if they are not operational while you're there, specific resort pools might.
Stormalong Bay at the Yacht and Beach Club will be closed for rehab from now through April 15th. Since this is known as one of the best pools and is even referred to as a mini water park, I would probably adjust my dates or change resorts.
I don't think there's ever a time you can visit Disney where nothing is closed because they're always working on something, but usually in the summer months all the resort pools are open and few rides are undergoing refurbishment.