I did it with the girls last year on a terrific travelzoo rate for three nights out of our summer wdw excursion. With two social butterflies of vastly different ages we ended making quite a few new friends during our stay. Everyone we met had a car, either a rental or their own. It's not far off the beaten path but pretty far out in terms of walking to eat somewhere, shopping, ect. I really wouldn't want to be stuck there without transportation.
It was great for the time we were there - and unlike other dis-ers I was very pleased with my room but then I didn't expect much after reading reviews.
We supplemented that time with outside activities. I'd think more than three days though could get very old, especially relying on busses to get to the parks. Plus many of the activities at the pool were planned mid-day so if you were in a park you'd miss the daily slime-fest at the pool (which is over in 15 mins anyway) and the games/contests.
I'm assuming you won't have a car during your trip b/c you asked about the bus. A nice compromise might be to book 2 or 3 NICK nights at the beginning of your trip and pick up a rental car for that short time, then check into something on property and use ME for the other airport transport when you leave. You can always drop off your rental on property and take a wdw bus back to whatever resort you are staying in or a park.
If you decide to stay the whole week at NICK, I really do think a car would not only save you time and aggravation but also money in food. The meal variety/prices at the NICK hotel didn't impress us but we did like the pools and room. DD18 noted immediately that there were very few teenagers to be found at the NICK (most of the kids we saw looked to be under 10) so if you have older kiddos that is something to be aware of as well. The lifeguards were 16-18 though and very friendly, chatting and playing with all ages.
DD7 is hoping for return trip this summer but I guess that depends on what sort of codes are out there this year. So far I haven't seen any real deals for our dates...