What's good:
It's right next to Ueno JR station. In less than 10 minutes, with a straightforward walk through some easily navigated subways you can be on the new Keisei Skyliner express train that take as little as 40 minutes to Narita.
The room was small but well equipped and comfortable and you can hardly hear outside. Only one pillow per bed plus a little cushion.
What's not:
That convenience is very expensive. The breakfast is atrocious. It starts at 7, and a line forms for that early, then it's a narrow line past a poor collection of budget-hotel style offerings and a bit of pasta. The tables are so close that you can hardly get in.
Service. I asked if they could print my boarding pass pdf. They smilingly directed me to a print shop over the road!!! My wife asked for help with the bags. They wanted to charge her.

We stayed at the Mitsui Garden over Mother's Day weekend. We had three rooms. The rooms are small compared to U.S. standards but standard compared to other Japanese hotels. Rooms were clean and service was excellent. Some staff spoke English. Hotel very convienent (Exit 1 on the Ginza line). There is also a Tokyo tourism office at the Ueno office. Yes - it will be nice for WiFi throughout the hotel. We got one of the WiFi "packages" but was not able to access from our rooms. Restaurants near the hotel were small that served mostly noodles. Enjoyed the easy access to/from the Tokyo Metro line.

Stayed here for 2 nights. It is very near from JR ueno station. About 5min walking distance from the station. You may see homeless at the station during nights. It is a walking distance to Ameyoko and Ueno park which we enjoyed. Ameyoko is always crowded but has tons of restaurants. We went to Ueno park during the weekends, therefore there were performances and dogs. Starbucks opened recently and the design is nice and open. We couldn't go in as it was crowded. Generally, Starbucks in Japan is often crowded. The hotel was not too small but sufficient. We reserved through online therefore the price was cheaper. They provide amenities for ladies which was great. There's a flat iron/waffle pajamas/magnifying mirror and face steamer. I pampered myself and felt so refreshed. Can be noisy at night with traffics but highly recommend. There's a metro just next to the hotel.