I'm assuming you did a search & didn't find anything?
I was there in February. It's ok; basic business hotel. Ironically enough, the Marriott Park Lane is closer to the Marble Arch tube stop than the Marble Arch Marriott. MAM is about a 5-10 minute walk to the tube. Solid 10 minutes to Selfridge's etc on Oxford street.
Somewhat small lobby. Had to wait to check in for room (and this wasn't an early morning arrival).
Rooms are ok, but small. Staff nice. Can't remember if they put paper outside my door or if it was just on table near elevators. Think it was the latter & it was tabloid, not the Times.
I used room service, which was ok. Didn't use hotel restaurants or the health club.
It's hit or miss on cabs being outside the door when you exit in the morning.
It's located in a middle eastern neighborhood, so most of the restaurants on the main street a block or so away are of that genre. and a lot of middle eastern folk stay at the hotel; this may or may not matter to you. i didn't care. was there on bizness & then switching to grosvenor square for the weekend.
They really hit you w/ high phone access charges (I was steaming when I got my bill at check-out & the phone charges are one reason I would consider not staying there again), so you might want to do the set fee for ethernet, which w/ the GPB/$$ exchange is still going to be a bit hefty. But UK hotels all nick you for phone access - MAM rate was higher than Grosvenor Square, and GSM is a nicer Marriott. But I've stayed at Hiltons where I got hammered on the phone access charges (ie, Langham especially). There are some internet cafes, which might be an alternative.
Can't remember if the hotel has a biz center or not.
They have doors that close in the hallways near the elevators in the evenings, to muffle the sound of the elevator. Since I had a room near the elevator, I appreciated this.
Hope this helps. Cheers.
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Sharon