I would definitely not call Skt. Petri a luxury hotel.
They market themselves as a 'design' hotel but it leaves a bit of an Ikea impression. The bathrooms are very basic.
However, the Skt. Petri is actually my favorite choice in Copenhagen due its excellent location. Having access to the new commercial gym on the ground floor is an added bonus for me.
Stars like Lady GaGa, Paris Hilton and Justin Timberlake stay here when in town.
Nimb is without doubt the place to go if you want luxury.