I'm here right now. It's nice, clean, relatively central, just about big enough (in my single room) & most importantly cheap.
If you're thinking of booking here, I'd advise you to at least look into "Shibuya Granbell", a hotel of similar cost and proportions (seemingly not listed on tripadvisor), only a bit trendier and slap bang in Shibuya. I think it would be a bit better for the party-going 20-somethings like myself, but the B would surely be better for those a bit older or after a more relaxed time.
I read some reviews stating it was hard to get to the b from the stations. Not so at all. There is one super-quick unofficial route (presumably not listed as you have to cut through a nursery.
Exit at Akasaka gate 7, take a right until you see some 'n' shaped metallic barriers, go up the flight of stairs past the weird cat-umbrella village, you'll see the b.
I'd say to improve, some form or wardrobe storage would be v.useful as I have had to open and close my case every time i have wanted anything, otherwise there is no space to stand. Under-bed storage would be a benefit too & the breakfasts could be a couple-hundred yen cheaper, or free as standard, other than that - can't complain.






Location


