I've stayed at the Stovall's quite a few times and the walk isn't that bad. I suppose it depends if you have walking issues. Our walks ranged in time of 12-17 minutes to security. It depended on how tired we were and how long to wait for the light.
Walking there is really easy....
1. Leave the Stovall's and cross the street heading towards the Paradise Pier hotel, you will also see DCA/Paradise Pier as well.
2. Keep walking towards the Paradise Pier hotel.
3. Once you get to the Paradise Pier hotel cross the street (if you are on the same side as the hotel) at the light and walk towards the Grand Californian Hotel (don't worry there is a big sign for the Grand Californian).
4. Go into the Grand Californian hotel lobby.
5. Look for the signs that direct guests to Downtown Disney and the parks, follow that and you will exit into Downtown Disney.
6. As of right now the stores flanking the exit area into Downtown Disney are Sephora and Ana & Elsas Boutique (helpful when returning at night to see those). Turn right towards Sephora and you will be heading toward the Esplanade and security check points for the parks.