Had a 5 night point redemption plus cash to secure a superior king room. This was the first of 5 Marriotts we were staying at over 18 nights. Applied 5 SNA's which were denied. Used the app to inform of an early 9 AM arrival and request early check in. Response was non-committal. Arrived. Fully booked. No rooms. Your titanium so here's a key to the chambers lounge. We coffee'd up then asked to have the bags held while we went to the library. It was a bit of an ordeal. They said they hoped to have a room around 11 AM. While in the library, connected to wifi and saw a message that the room was ready and we were in by noon.
Third floor Barlow facing the library. Room had a lingering smell of cigarettes. Bottled water and Nespresso machine in room plus cookies refreshed daily. No note or thanks for staying. Bathroom is a bit small but room had the space we required. The base queen room wouldn't have cut it. But it was a bit tired. Our sink was clogged so we reported it. It took 3 requests with different folks to get it unplugged.
We checked out the spa, did use the gym and it is nice. No treatments booked or use of the pool but if that's your thing go for it. They seemed top notch.
The folks working the Chambers Lounge were very nice but I did not learn until the last day that you can request eggs to order. The evening beverages were refilled frequently but it did get a bit busy. Usual breakfast fare of hot and cold items. Evening food was good and treats were delicious. That said, the lounge made the stay for us. Great place to relax after a day on your feet touring. It is a grand hotel near lots of shopping and sights. Walkable to the British Museum and found some good pubs and restaurants nearby (Lord John Russell pub and North Sea Fish) away from Coal Drop Yards. We did not use the Booking Office for breakfast or at other times but it was always crowded.
I probably would not stay there again except before or after a Eurostar trip. Clearly their focus is on events and there were plenty during our stay in the ballroom, the rooftop garden, staircase area etc. If you are in the area, stop in just to check it out as architecturally it is a gem. There's plenty of other places to stay.