Stayed at Polynesian with 4 yr old from Aug 12-16.
1) On the Monorail system which allows you to make it Magic Kingdom (MK) in 5 minutes. We want to MK one morning just to re-ride the Barnstormer and then returned to the pool. The round trip including a ride both ways to the Barnstormer on the Magic Kingdom train and 2 rides on the Barnstormer was about 45 minutes.
2) Excellent pool with water slide
3) Easy access by Monorail to Epcot
4) Nice grounds and updated modern rooms
5) View of MK fireworks from the beach
6) Multiple restaurants on site
7) Knowledgeable staff
8) As with all Disney resorts you receive additional perks (i.e. airport transportation, extra magic hours etc.)
9) Store on site to buy drinks, chips, baker etc. albeit at Disney inflated prices
Cons: 1) No computers available in lobby to access internet (there is a line in the room if you bring your own computer)
2) Price - This is a "deluxe" Disney resort. You have to pay for the above pros and for the Disney name.
3) There is some construction currently in process, which is noticable, but does not otherwise affect service etc.
Keep in mind that dining reservations for popular restaurants throughout Disney, including at the Polynesian, are best made far in advance.