It is all it's advertised to be. Spectacular views, charming cities and it's easy going BUT it's pricy and don't be on a tight schedule. Take your time to visit. Arrive early and leave late.
We opted not to stay on the island but the cities and venues are remarkable.
GETTING AROUND
We took the ferry as a walk on passenger (no need to reserve but do get there 30 min before) - nice 45 min ride that goes by so fast.
On the island, you can take Tours, Scooters, Rent a Car, Bicycle, UBER or public transport. If you are on a tight schedule and want to explore, I would strongly recommend scooter, car or uber. Public transit is very good but if on a tight schedule you will only skim the surface of this magnificient island. Same for a paid tour.
Public Transit - option we took, only 8$ for the day and good service but we were on a tight schedule so had to take UBER for 1 trip from Edgartown to Aquinnah to make it more time efficient but if you are not on a tight schedule, public transit is excellent.
UBER cost us $66 USD from one end to the island. Very good option to avoid missing a bus (tight transfer schedules)
Tours - you only skim the surface of the island but it's no hassle.
Scooter - seem fun, but main roads are very narrow so somewhat not secure. Also, very expensive.
Rent a car - good luck, reserve months in advance and very expensive.
Bicyle - good option. Many cycling paths.
If you are well off financially or want to make it memorable, I would recommend renting a Jeep or convertable. It is the perfect setting to do so in the summer.
VENUS
Oak Bluffs - nice litte coast line city. Beautiful coastline housings. Commun Street is a cute little place, but mainly shops and stores. Cute little beaches as well. If you don't go to the beach, I think 1 hour is enough in that town. If you go to the beach, it changes duration time. Water is clear, beach is sandy, not too rocky.
Edgardtown - I prefered it compared to Oak Bluffs. This has more of a fisherman town feeling, but OMG the streets, houses, docks, marina, restaurants, lighthouse are unbelievable. I'd recommend spending min 2-3 hours (if not rushed) if you want to eat or drink there and tour around.
Aquinnah - THE PLACE for natual scenic view. Amazing lighthouse, nice beach (rocky sand) with stunning multicolored cliffs. True beauty. take the time to talk on the beach and walk around the cliffs. Since its a rocky sany beach, bring water shoes for a more comfy walk. Water is warm. First 2-4 feet into the water is rounded soft rocks but after that it's nice sand. I could spend half to a full day there to enjoy scnenary and relax. Don't expect a town, it is seculuated with basic foods amenities but the beauty is remarkable.
The UBER driver was telling us about Chippaquiddick Island off of Edgartown. Ferry is about 5 minutes duration. Apparently amazing and worth seeing. Recommendation transportation on the island is renting a bicycle. Next time, it's on my to do list!
TIGHT BUDGET OPTION
If you have a tight budget and can't afford sleeping on the Island, another option is lodging at Wood Hole (where the ferry is) or Falmouth (free shuttle to the ferry) and go back and forth between island and your hotel. You can cut costs by half doing so BUT don't be pressed with time because you have the 45 min ferry back and forth to consider, but if you want to fully explore Martha Vineyard over a long weekend, it's a good option.
Have fun.