First of all, I will say that I'm an owner of a timeshare here for about 10 years, but I stayed here prior to owning. Nonetheless, I think I can give a fairly balanced review of this establishment.
The Harborside Inn is a converted motel, compriseharbord of old sea captain's mansions as well as some new buildings. Currently it is a timeshare resort as well as a hotel. Those who own weeks who choose not to use their week can let the Inn rent the room out. The owner of the week takes a cut and so does the hotel. That which goes to the hotel goes toward the general fund which goes toward upkeep and paying salaries. The rest of the costs of operation is paid from maintenance fees paid by owners.
The rooms are clean, but not huge. They are either individual rooms in the old homes (which are very charming) or rooms in the newer buildings. There are a couple of rooms that have an actual bedroom in addition to the main room so they could house a family, but most rooms are the equivalent of a hotel room, with only a mini-fridge.
The grounds area is pretty immaculately kept. There's a nice small pool, a small inside Jacuzzi, and slips for boats, which can be rented for an extra fee.
The location couldn't be better, right smack in the middle of downtown Edgartown, where the boutiques and galleries are, and right on the waterfront. That's what you get for the premium price -- the location. Plus the pool and grounds facing the harbor, and you're all set.
There is no restaurant on the premises, but there are places that will deliver. You are steps from a variety of eateries, from medium to very upscale. There is a large common area in the main building and a large deck facing the water off of that. The view is pretty terrific from there.
There is free parking, but the lot is about a 5 minute walk away.
The key to getting value, to me, is opting for a street view room. The highest priced rooms face Edgartown Harbor. Getting a room in one of the captain's homes that faces a Victorian era street? Charming... and cheaper. The rooms that face the water do have the advantage of a balcony, but the rooms facing the street (in the original homes, not in the newer buildings) were the larger and better rooms in the original homes, many with original period detail.
Go off-season, either April-May or October-November and you can likely get a better deal.
Rooms get cleaned daily, and the staff aims to please.
More luxurious accommodations might be found at the Charlton Inn or Harbor View hotel, but the central waterfront location with pool and nice grounds of the Harborside Inn is unique to Edgartown. If you plan to bring a boat here, no other accommodation in Edgartown has its own boat slips, so that could be a factor in your decision as well.