My girlfriend and I stayed at the Arcotel Rubin hotel for 3 nights in the last days before christmas at a discounted price. The room is very nice. Clean and spacious and the bed was very comfortable. I asked for a room with a tub and got it which was nice. I did miss some coffee making facilities, which is usually provided for standard room in most hotels of this standard. However, in Arcotel it is only available if you upgrade.
Wifi was working excellent. I did not try the breakfast (20 euro for regular and 9 euro for some sort of 'small' breakfast). There is a place called Back Factory nearby, which sells bread/sandwiches etc.
The area is a typical german casino/grocery store/sex shop/kebab store street. A few prostitutes here and there, but nothing that makes you feel uncomfortable at all. Location is very good, in walking distance to the main train station and central shopping area.
The biggest minus for this hotel is the expensive parking basement at 16 euro for 24 hours. Maybe you can park for free somewhere nearby, but did not check it out. However, I believe most hotels in Hamburg will charge you between 10 and 20 euro a day for parking.
Overall, I would definitely recommend this hotel. For the price you're paying, it is a good choice with a good location. Enjoy.