I stay at this property all the time (monthly). It's a nice place. There are two towers and all rooms have been updated. All have decent wired internet and no extra charge for wireless use in the lobby and lounges. The tall tower has the regular rooms and the short tower has the executive level rooms (the whole tower). The exec lounge is very nice if you book executive rooms or have status.
More than half of the rooms have views and they are nice views.
There are nicer properties in Doha but you will probably find their rates to be higher. I think the Marriott is a good compromise as it is a good facility and usually reasonable rates, especially if you make a group deal. Meeting faciltiies are fine. The spa is very good and there is pool and beach swimming. The gym is so-so, but acceptable. Food is very good throughout the hotel.
Like many hotels there the staff can really vary. Some are nice and helpful but there are also major gaps in service.
One drawback is that there is really nothing nearby to walk to. Other hotels on the corniche (Sheraton, Four Seasons) offer much better walking.
The Four Seasons holds the top spot for meetings in Doha, but my guess is you'll pay 50-100% more there considering rooms, meeting rooms, and food.
Book any meeting well in advance for Doha. There are only a few hotels and once they get booked, you are in big trouble.
Feel free to PM me for more info.
Charles