We stayed here for 2 nights on the tail end of a two week trip around Osaka and Tokyo. The room size was fine (we had #328), and with two large backpacks between us, we didn't need to use the under-bed storage space. Beds are comfortable enough, though quite hard (I actually prefer this over soft beds, but it may be an issue for some).
Breakfast was simple and filling, but most definitely Japanese style only, in spite of what the information slip given to us by reception said.
Location-wise, the hotel is very convenient and there are a number of Family Mart/7-11 etc nearby. Ikebukuro station is a 5-10 minute walk but you need to make sure to take the north exit because the station is so huge. At ikebukuro you can get on the JR Yamanote line and also some of the narita express direct trains stop there.
Unfortunately, the bathroom was really quite smelly, to the point that it was better to leave the door closed. It wasn't dirty, but smelled as though the drains were blocked. Also, the main bathroom drain is lower than the plug hole in the bath, and so on draining the bath water, it all bubbled up out of the main drain, leaving our clothes, which were on the bathroom floor, sopping wet.
Obviously these aren't major problems, and had we been staying longer I probably would have asked for a room change because of the smell in the bathroom, but I will probably look for another place to stay next time I'm in Tokyo.