The hotel is new and very clean with good facilities. The fridge in the room is useful. The staff are very friendly and helpful and extremely polite.
The location is good as it is close to the train station and pretty central to everywhere.
I would recommend this hotel.

Stayed in the Mitsui Garden Yotsuya for eight nights around New Years 2011-12. We were very pleasantly surprised, even after having read the many positive reviews here.

Rooms are modern and very clean. They are indeed small (you wouldn't be able to keep two large suitcases open at the same time), but efficiently designed. Special mention goes to the toilet (in good Japanese fashion with heated seat and plenty of buttons that do unspeakable things) and the toiletries, that included toothbrushes, mouthwater, and a razor including shaving cream. Free wired internet was a nice bonus. Staff was very friendly and helpful, and their English was more than adequate.

Location is spot on for JR and subway connections (two seperate stations; as one reviewer already mentioned, upon arrival, look for the KFC-sign and the hotel its two minutes up to road from there). We didn't have breakfast in the hotel, but there's a good "Café de Pudding" (really, that's the name) across the street that has good sandwiches and pastries.

All in all, great choice, excellent value for money.

Finding an inexpensive hotel in Tokyo can be tricky, however this hotel was great value for money and a lot more boutique in style than we were expecting. It was lovely, clean, the food was good and the complimentary toiletries were fantastic. It was also really quiet even though it is on a main road.

The location is great too - you are very close to everything, whilst having the benenfit of being out of the really expensive accomodation zones such as Shibuya.

Yes the rooms are small, but that is typically Japanese. The train station is only a couple of minutes walk away, however I would recommend that any traveller read up about the Tokyo subway system prior to travel as it can get a bit confusing as there are sevel train lines operated by different organisations meaning you need 2 separate rail maps to get around!

I would definitely stay here again, and would hope the other Garden Hotels in the chain are of a similar quality.

The Mitsui Garden Hotel Yotsuya is part of Mitsui Garden hotels with facilities across Japan (5 in Tokyo). I stayed at this hotel in November 2011 and was very satisfied. Location is a key strenght of this hotel but let me explain you clearly this. If visiting Tokyo for the first time, you certainly might consider staying in one of the various "centers" of Tokyo, for example Shinjuku, Shibuya, Ginza, Ikebukuro. You would have the advantage of returning to your neighborough to explore during the evening/night and not care about metro/trains stopping service after midnight. However, if you are not a "night explorer" like me, and you prefer easy reach, then the location of Mitsui Garden in Yotsuya is excellent. In fact, the hotel is just five minutes from the Yotsuya station, a mid size train hub with two of the most important JR lines (Chuo and Sobu line) and two Tokyo Metro subway lines (Marunouchi and Nanboku lines) which basically mean you are on two of the widest reaching urban transport systems in Tokyo. I found that when staying at this hotel I could easily reach any area in a relatively short time. OK, in Tokyo you never have issues with metro/train transportation. But here it is even better. I could choose between Ginza and Shinjuku and it would take no more than 10-15 min. Shinjuku is 5 min on the Chuo (Express) just one stop. Ginza easily reachable directly by Maronouchi (10-15 min). Different options to get to Shibuya either changing at Yoyogi on Sobu line or by a combination of Tokyo metro lines. Akihabara 10-15 min Chuo line and then change to Sobu at Ochanomizu. In short, Yotsuya is quite central, closest to Shinjuku but within the Yamanote loop so also east side of the city are within easy reach. The hotel per se is very nice and modern. A clarification needed. This is not in Shinjuku and be aware in Japan check in time is mandatorily after 3pm. Rooms are small but compared to Japanese business hotels I have been several other times, these are larger, clean, modern with LCD HD TV (only english channel BBC World however), nice shower (my room was a "comfort room"), mini fridge, slippers, yukata. The hotel is on Shinjuku dori, which despite its 6 or so lanes I found astonishingly quiet especially in the evening. My room was on the back street, and despite some works in progress on the road a couple of nights, was very quiet. The hotel seems new, reception staff very courteous and helpful. My room price did not include breakfast, but I found convenient having breakfast at the hotel restaurant "Pizza Salvatore Cuomo" for 1000 yen. Breakfast was quite good with a western buffet choice (including croissants, ham, yogurt etc) and a nice choice of fruit, vegetables. Other options for breakfast include Doutour just 1 min walk and other nearby eateries including Yoshinoya, KFC. Different convenience stores (Family Mart). I enjoyed the Yotsuya neighbourough when returning in the evening from the more bustling areas of Tokyo, landing in a quieter area was nice and helping to wind down before sleep. Just behind the hotel there is a small street full of small restaurants/izakayas, just parallel to Shinjuku dori, which I found very nice.
One last plus, coming and leaving Tokyo by train (I used NEX), I did not have to do a single staircase with my luggage!: escalators at Tokyo station, escalator at Yotsuya and walk out on slightly climbing path out of the station, pedestrian xing and then 5 min pavement walk and was at the hotel.
Overall, highly recommended convenient and affordable hotel perfect for the expert Tokyo explorer not having to stay mandatorily in one neighbourough and willing to have a central hub from where reach to the different Tokyo areas.