Will the motherboard fit inside, and leave a little bit of room for your fingers, and, able to fit a CPU heatsink fan, and, close the case?
Will the hard drives poke out over the motherboard, right where you need to install your 'long' graphics card?
Can you install the power supply unit and be able to tidy up all the cables?
Some decent cooling is ideal, needs to be quiet.
A side window does not conform to EU regulations?
Personally I don't care what the case looks like as 98% of them are all the same inside ... I look for practicality.