To start, this review is based on staying at Kleine Gracht 10B in Maastricht. The way Residences Maastricht works is that you book an appartment via them, but you don't know in advance which of their appartments, as they have several in Maastricht. So it's possible that you have a different experience in one of the other appartments.
Having said this, our experience at Kleine Gracht 10B wasn't very good. Sure, there are positive points as the location of the appartment (city center, 5 min walk of the Vrijthof), free wifi, airconditioning in the bedroom and the fact that you have a livingroom, kitchen, bathroom and bedroom. So if you stay longer the essentials are present.
The downside is that it's a bid worn out, the bedroom is equiped with two beds put together (you can only enter on one side or at the foot end) with different matresses of which one should really be replaced.
But the worst was that the appartmentis not clean: in the bathroom was a layer of dust and hairs presumably from more than a week... We had the impression that the only "cleaning" being done was replacing the bed linen and the towels. Reporting this to the staff didn't lead to any action or appology, which in our opinion should be the standard reaction if you're taking your hotel business serious...
We visit Maastricht 3 to 4 times a year, and there are a lot of better hotels and appartments, with definitely better value for money.