There are two Vistana properties in Orlando.....the Sheraton Vistana
Resort (which is very close to DTD) and Sheraton Vistana
Villages (which is closer to SeaWorld). Which one is your offer for?
We own at SVR, and absolutely LOVE IT there. Assuming its the Resort that you are considering, there is a great thread on these boards with tons of photos and resort information which you can find here:
http://www.disboards.com/threads/the-sheraton-vistana-resort-thread.3148502/
There are two types of one bedroom villas, one which is much smaller than the other (400 or so square feet with a kitchenette and no balcony, versus 900+ square feet with a full kitchen and balcony). We stayed in the larger configuration last May and thought it was great. A one bedroom villa would guarantee you to be in either the Lakes or Cascades phases, both of which have elevators in each building.
The timeshare pitch, if you have to go to one, isn't bad at all. We did it once, and it was 90 minutes on the dot. Not high pressure and very civilized (especially when comparing to Westgate....aye yi yi

).
The resort is beautiful, the amenities are INCREDIBLE (7 pools, 6 hot tubs, 13 tennis courts, 2 sand volleyball courts, 2 basketball courts, shuffleboard, multiple playgrounds, daily scheduled activities, mini golf, farmers market, onsite store that serves Starbucks coffee, etc.), parking is free, internet is free, and the villas are marvelously well appointed. We have stayed onsite at Disney, and the tiny rooms just can't compare to the SVR villas. As long as you don't mind driving to the parks, you're golden.
And.....the north side of the resort is right next door to one of the DCP residences (which one is your DD staying at?).
I wish I could snag a deal like you've received.....we need a second week in October and that price point is right in my budget!!!