There are a few reviews posted on the Marriott Budapest Hotels thread, but no master thread, it seems.
Convenient location, near tram and metro. Above a shopping mall. Huge number of restaurants in area too.
Stayed using point breaks (22,400/night) for two nights. Attached two upgrade certs and got a suite. Not the newest interior, but spacious enough. No charge for 3rd person using sofa bed.
No free breakfast, but the $10 per person credit per day meant 50% off the breakfast buffet (which was good).
Welcome drink was house cocktail.
Would stay again given the price (cash rates also reasonable).