House rules within the development e.g. re satellite dishes, pets, common areas, rules specific to the development.
How regularly are the common areas serviced/cleaned, common windows cleaned, bins emptied?
Is there onsite security, onsite caretaker?
What are the parking rules. Is it designated parking only? Is clamping in operation? Are there any visitors parking spaces? Ask to see them. Where is your own designated parking space (if its included)?
Any safety concerns you might have with getting in and out (e.g. is the path from your car to your front door well lit - think about how this would look at night).
How many other apartments are in the same area as you (noise of multiple doors opening or closing)?
Noise levels (open the windows and see what noise comes in from outside).
Who are the management agent? What other developments do they manage? What is their track record? (You can probably do your own research on this one!)
Internally (not sure if you need this too):
Check for storage space, wardrobes cupboards etc.
Check water pressure (is there a pump for increasing pressure).
What kind of heating - gas or electricity?
Quality of kitchen whitegoods (if these are included).
Is there a dryer? If not, where would you dry clothes (most developments ban hanging clothes out to dry on balconies)?
Kitchen cupboard space (is there enough?).
Don't be either blown away or put off if the place is currently furnished. Think of how it will look with your own stuff inside. Its easy to be blown away by the lovely furnishing in show apartments! Its equally easy to be put off by someone else's taste in furniture. You are not (I'm assuming!) buying the contents!
That's all I can think of for now...I'm sure there are tons more! Hope its helpful! Good luck!