The hinge is fine. The locking mechanism is poor in my opinion. Needs a vape band if you plan to pocket it.
Or a side-by-side mod

I haven't had any problems with the Nano so far, but I must admit I see the full size version as my relaxing-at-home-tank. Partly because of the hinging top but also because it sits freaking high on my mod! It tips over much quicker then with the Toptank for example.