I stayed here for two nights and a day and found the hotel to be excellent in value and location and service. I'm not sure where the negative reviewers have stayed before or what they expected, but the JWM exceeds many other hotels in Rio, if not most.
The hotel is pretty new (around 10 years) and is in great shape and has everything you could want. The staff was excellent and most speak basic to adequate English. Check-in was fast, but the key machine was broken and I needed an escort whenever I entered my room until it was fixed (about 2 hours).
My room was an ocean view as I wanted light, but others told me the interior rooms are not too dark, so not sure if the view justifies the extra cost. Yes, the rooms are small for what you pay, most hotels on the beach have small rooms. The bathroom was quite large, accounting for 25% of the total room space. They have an iron and ironing board, coffee maker, desk, chair, and a very, very comfortable bed. The air conditioning worked nicely and could be adjusted easily.
I had dinner at the sushi restaurant and found it to be average, but the waitress made up for this in friendliness. Breakfast was included and had a wide assortment of fruit, meat, and an omelete bar.
The pool area and spa were nice and big for a hotel in Rio (don't be surprised by the 8 ' by 20' pool). The bar staff at the pool bar are a bit pushy, after all, who orders a beer when their glass is half-full (maybe he thought it was half-empty).
A really nice thing about the hotel is that they let you use the pool/spa after you check out. Since most flights leave Rio later in the day or evening, having the chance to relax, shower, and leave feeling fresh is an added touch that many hotels do not offer (without charging you a half-day or a spa charge).
Two items to note. They had an odd system of charging my credit card before showing me the room charges (I didn't think to ask for them as this has never happened before). Alas, there were some "extra" charges that took about 20 minutes to delete and then credit back to my card. Also, the JWM is part of the clique of hotels that feels that it has to gouge customers for internet (18 USD a day). When will this stop?
In a few words: worth the price, great staff, comfortable bed, very quiet rooms, nice pool, great place.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.