Had a recent stay here and was upgraded to a studio. Size-wise it was very nice, I was a bit surprised by a lack of sockets. Internet was not ibahn, but good in speed.

The Executive Lounge was actually the best I experienced in a Marriott so far (Better than current Berlin). Breakfast was very nice with the option to get eggs-to-order from the main restaurant (as a Plat you can also have breakfast there), but I was completely awed by the evening selection. On the hot side it was "just" a meat dish and a veggie-dish, but the quality and execution was top-notch. One day they served beef, and it was perfectly cooked and melted in your mouth.
In addition they had a selection of cold snacks, and the usual drinks (one good white, one good red, Rotkäppchen sparkling, Beer and non-alcoholic).
Staff was very nice too, sometimes a bit rough on the edges, but in a good way.

Cheers,
starlicious