Not infrequent leaks, the bathroom had no windows so loved to mould as fast as it could, the boiler broke a few times though this is tied in to how bad the agency was.
Other identical houses of the same terrace has big damp streaks down the front face of them. Cracks were appearing where the skirting board met the walls, etc - couldn't say if that was poor joinery or if the entire thing will eventually come down.
The actual design of the house wasn't bad. Being a relatively new build the insulation was better than some, worse than others.