Would not recommend it for a stay longer than one night, especially not for attending venues at Messe Berlin.
Difficult to get to by foot (at least 15 min from nearest S-Bahn station), surroundings a little sketchy (mainly streets, one narrow stair at the North-East end of parking lot, way across motorway parking lot with partly broken lights, stair even blocked by parking bus once) though safe.
Noisy (right at motorway) even with closed windows, no air condition, no darkening curtains.
Room superficially clean, curtesy water bottle closed with crown cork, interior of cupboard dusty (but needed).
No possibility to skip every-day service (not necessary, but more thouroughly cleaning after visitors adviced).
Good: Bed linens and towels clean, bathroom clean (but lacking hooks), solid mattress.
Breakfast caters mainly to professional long distance drivers (eggs and bacon, barely fruits).
Highlight: Very friendly staff at breakfast.
Bottom line: Bargain, ok for one short night while travelling.