I stayed a week at Keita's house, and overall it was a great experience. Keita was excellent with communication and explained everything on the first day. The location may seem a bit on the outskirts, but the subway system keeps everything very well-connected. Major areas like Shinjuku and Shibuya can be reached within an hour of leaving the house. Even the area around Minamidaira station has a number of things worth seeing (parks, temples, a zoo, etc.). The only potential drawback is that the house is near the top of a fairly steep hill, so I'd suggest getting a ride up when you first arrive, especially if you have heavy luggage.