There are tons of Wes Anderson fans that wish they could give a real Grand Budapest Hotel review of the Hungarian hotel, but it's sadly only real in the movies. However, you can still leave your two cents about the accommodations as if you really did book a stay there through TripAdvisor.
As of now, the hotel has a glowing four-and-a-half score and an overall rating of "excellent." The TripAdvisor page for the fake hotel includes fan reviews that relive fictional vacations, bad experiences with the hotel staff and point out excellent examples of customer service. To reiterate that you can't actually visit or stay at the Grand Budapest Hotel in the Republic of Zubrowka, TripAdvisor excludes prices from the page, but otherwise, the reviews—good and bad—make it all pretty authentic.