The VZ is the last of the VT series. As there have been 3 previous models to work out the bugs, a VZ is generally considered a pretty safe bet. It did introduce the Alloytec engine which may be problematic for some. There is also no series 2.
02 sensor wiring melting due to making contact with exhaust manifold heat shield
Faulty fuel gauge reading, some can overstate how much fuel is in the tank
Water leaking into the bootlid
Rattling steering column have been reported when driving at high speed
Flaking paint on door handles
Timing chain issues with the Alloytec engine
The gear box can be noisy, especially the manual
Shuddering on take off due to improperly fitted tailshaft
Warped brake discs