Premium is the way to go! This is the second Premium Dormy Inn that I've stayed at (other in Kyoto) and both times I have been extremely satisfied with my experiences.
I didn't realise until I arrived that this hotel is new (and new, not just refurbished), opened April 2012.
note: the hotel is closer to Harajuku Station (and downhill 7mins; slightly uphill from Shibuya, 12mins walk approx.) There is a free shuttle every 30mins to take you back to Shibuya in the mornings.
Desk staff were welcoming. The man that served me seemed to speak a decent amount of english (we used mostly japanese). There are computers in the lobby, as well at a seating area with free tea/ coffee, and from 9-10pm there are free hot soba noodle bowls served (I didn't actually partake in either of these services).
The room: small double, but really, I didn't need any more space. Lovely big OPENING window (I hate when hotel windows don't open) HOWEVER, the window glass was frosted, so impossible to see out to see what the weather was like etc. I partly understand the frosted windows, inner-city, right by the train line, and the side I was on (northern) overlooked a cemetary.
Nighttime noise: you could hear a little of people up and down the hall, but not too noticible or annoying. The Yamanote Line runs right past outside, the trains themselves are very quiet; so with windows closed it was no bother. Windows open, and still no more noisy than usual vehicle traffic sounds would be. Actually, the hotel is not on a main road, so there was no road noise at all (heard a couple of sirens, but not disruptive, and usual for any city).
Onsen: great perk of the Premium brand is that they have onsen (hot springs). These were internal on the second floor of the hotel. Separate mens and womens baths. Security code entrance doors, the codes are renewed each day. Normal japanese style public baths. I like the decor, dark tiles, with windowed garden between the bath and the 'dry' areas. Fresh apples where floating in the bath, nice seasonal touch. Nice soap, shampoo, conditioner available for use.
The whole hotel was very clean, english information readily available, comfortable and convinient to stay. I'd highly recommend the hotel to anyone.