I stayed there for 3 nights. The hotel is just next to the subway Higashi Shinjuku station and around 20 mins walk to the JR Shinjuku station. There are some restaurants and convenience store nearby. As I know most of the hotels in Tokyo are with small rooms, I don't have much expectation of the room size. Although the room size is small, the room is still clean and comfort.
But DON'T open the window, the hotel is in front of a busy road, it is quite noisy outside.

I wanted budget accommodations, but something nicer than a hostel, reasonably close to a major sightseeing district and a stone's throw away from a subway station. My search led me to Sunroute Higashi-Shinjuku, at $75 USD per night for a single room.

I was expecting a cramped room, but honestly it was a reasonable size for a single. The room was spotless, and the bed was soft and comfy. The reception spoke great English and made me feel welcome, and even helped me with suggestions on local izakaya/restaurants.

The only downside was that subway access from the major tourist attractions is a little more involved. Getting to Higashi-Shinjuku on the Oedo line from Shibuya or Tokyo Stations, you'd have to transfer at Tochomae. A minor inconvenience, really.

In the end, it was a very nice business hotel with an unbeatable price. I enjoyed my stay, I've recommended it to my friends, and I'll definitely consider it on my next visit.

Stayed 6 nights here and would recommend it for a low-cost option in a good location. Several nice touches that you normally expect to spend more money for. There was quite a lot of noise on the road outside during the night (sirens, roadworks) but this is central Tokyo.

We booked this hotel based on the enthusiastic reviews. Well, as much as the place is fine, it doesn't deserve all the kudos we read...
Room was "large" enough (by Tokyo standards), and quiet (we had required a quiet room at booking and that was addressed).
TV has only Japanese channels.
Location is perfect, over Subway station, and within walking distance to Kabukicho and Shinjuku.
Good bedding.

The bad part is communications:
1) no wireless internet at all. That means that if you use a iDevice, you are incommunicado for all your stay.
Only 2 slow and busy PCs in public use in the lobby.
2) the local phone calls from the rooms are outrageously charged. Use public phones instead.

Good base to spend a sightseeing / shopping week end in Tokyo.
For longer stay and if communications are needed, might not be the best choice.