The M Hotel is basically fine. The room is nicely designed, although it is a bit worn down. The location is good, with easy access to many places.
However, there is one issue I cannot ignore. The reception charged an extra €16 for having separate beds, even though the booking confirmation clearly stated two separate beds. This was not indicated at the time of booking or in advance.
I hope the hotel will look into this case, as this is not a fair practice, and I would not like other guests to experience the same. It is worth checking the bill and booking details upon arrival.