Stayed there for business purposes. Great location for visiting Deutsche Telekom or T-Mobile close to train station. Breakfast was absolutely amazing, this was the best part of my stay. Rooms need a major overhaul and update - I thought I was back in 1987 with the decor.

I stayed here about seven times since 2006--several days at a time. I like this hotel; rooms always comfortable and clean, and the window opens. I've always had two single beds. Hotel is a 5-minute walk to the Darmstadt train station--excellent connections to anywhere, and less than 8euro bus ride to Frankfurt Aeroport. (bus also picks you up 50meters from the hotel as well as the train station). Newstands, internet, and cafes also at station. A previous posters noted taxis are needed to go into town; I personally enjoy walking to city centre, but it is at least a 20min walk. My colleagues and I walk to/from dinner every night--always enjoyable and safe, and it mitigates the heavy German meals! Hotel bar not bad, & you can order food there. Hotel breakfast is excellent and ample buffet, with attentive table service for coffee. Nice pool and sauna on top floor. Front desk staff always pleasant & helpful, with excellent English. Yes there is constant train noise; I'm always on trainside, but with window closed it is not excessive--at least on 7th floor. You could always request the front side of hotel (away from tracks), which would have no noise..
There is also closeby the other Maritim (Konferenzhotel) next to the train station (stayed here once when other was full). Konferencehotel has little balconies which are pleasant.

Stayed at the maritim rhein main for three nights for business purposes, so the room was really just a base for four days.
The hotel location is on a main road close to the railway station. The train tracks run along side the hotel. It isn't particularly close to any restaurants/shops so be prepared to take taxis into town. There is a good pub opposite the other maritim (konferenzhotel) which (as you can see on a map) is nearly opposite this hotel.
The hotel food was good, i had dinner there twice and thought the standard was excellent-although the menu was limited. The breakfasts were ok, buffet type setup, cereals and fruit and some hot food. There was fruit juice and coffee available, can get busy as everyone is in there at the same time for work/conferences etc.
My room was tidy and cleaned every morning, i was on the 7th floor so although my room faced the railway any noise was limited, good views over darmstadt. Tv had 2 english channels for anyone that wants to know.
Plenty of taxis available outside the hotel in the morning. Depends who you get on reception to the type of welcome you receive.
Overall a good stay, would stay again although now i know the area a little better i might chose one in the town next time for options in the evening.

RECOMMENDED Not many choices in Darmstadt, especially if you are visiting T-Systems/Com (a short walk). Frankfurt airport bus stops directly in front of property. Check-in prompt. Room very large. Nice bedding and bathroom totally acceptable. HINT Ask for a room not facing the railroad tracks, constant rail traffic. Breakfast buffet nothing special, despite all the grandeur.