i stayed a few times at the Stallmasteregarden, albeit some 5 years back.
Of course this is not your typically business oriented hotel but more of a boutique/family run property.
I really really liked the place a lot. Nice rooms, great food and beautiful location, however,
- make sure you have a room facing the lake or inner court and not the street,
- accept the fact that it isnt really a central location and
- that it can be a bit noisy, as it is indeed bordering onto the highway that heads out to the airport.

I would go again though, absolutely no doubt about it.
Come to think of it i had some of the best food at that hotel.
And being an SPG "slave" for many years now, I spent more nights at this place than at the Sheraton, which should give you an idea.