I frequently go to Luxembourg for work, and this was the first hotel I tried. I have since tried four others (only when Hotel Francais is fully booked), and this one stays firmly at the top of my list after several years of twice-yearly visits.
The location is unbeatable, the service is excellent (once the night porter fixed me breakfast because I had to get to the airport so terribly early), and the rooms are clean and comfortable.
Of course, because it is so central, it can at times be a bit noisy (I've had my share of Christmas fairs and drunken football fans outside my window!), but it hasn't bothered me much.
