Nikon D90 users, please help me

Good day, I would like some information please. I am considering jumping ship from pentax to nikon, for reasons of persistent pentax problems from model to model.

I would like to know if the D90 has the following problems - FF or BF under different lighting conditions or with specific Nikon lenses, variable exposure metering results under similar conditions, problems with flash performance e.g. inconsistent results or consistent over or under exposure and in general any common operating problems, for example I read about the camera freezing and needing to be reset to be used again.

Many thanks in advance
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jamesza