A great opening scene and an amusing end scene aside, 'The House of Magic' isn't anything I'll remember with that much fondness.
I will say the animation is much better than I had anticipated, it's nothing near a high level but it is absolutely fine; nothing bad about it in truth. The cast are serviceable if forgettable, I wouldn't say any of them are better or worse than their colleagues - which I suppose is a minor positive, given no-one grates with their voice performance.
I found that the mesh of plots didn't work as good as it possibly could have, granted it isn't terrible but we don't really get enough of either in my opinion. A bit of magic and a bit about the cat's story, it ends up just becoming a standard lacklustre and predictable villain-centric plot.