Stayed there for 2 nights - pre-selected room on the App. Upon arrival, I asked about lounge access and the front desk agent upgraded me to the executive room as a Gold. Was also offered 2 bottles of water at check-in.
Lounge won't open until 2pm due to the holidays - we were offered breakfast in the Garden Restaurant. Breakfast spread is good - full English, bread corner, oak meals, salad. I found it is at par with Hilton Canary Wharf.
Room at the new wing is good - clean but a bit tired but I found it adequate. I left the room at about 1pm and found the room didn't get refreshed. I called and it was refreshed in about an hour while I am retreating at the lounge.
During 6:30pm to 8:30pm the lounge was kind of full. Full bar was offered along with canapes and a mushroom soup. Lounge attendant was nice.
Found the cheapest way to go to central London is to buy a roundtrip ticket on National Rail - 13.6 pound round trip plus a couple more with the travel card option. Oyster will cost 8.1 pound one-way. I believe oyster is capped at 19.3 pound daily. It takes about 45 minutes from Gatwick airport station to Central London with a change of train at Chapman.
I would stay there again.