It is a large development with hugely varying experience across different complexes and even different blocks within the one complex. My experience would be of very little anti-social behaviour around the living areas, possibly more around Eurospar and McDonalds. There is security that patrols Northwood and while I doubt they would stop incidents, their presence discourages trouble. I have very occassionally heard of trouble with cars but would more frequently hear of bicycles being stolen.
There are a lot of rental properties, around 80% in some of the developments. Different management companies enforce their house rules to varying degrees and this really impacts the quality of life whether the apartments are owned or rented.
Be aware that some parts of the development have issues with pyrite so very important to check that - as far as I am aware it is limited to a small part.
Overall it is a nice setting, accessible, plenty of green space, good access to public transport. It seriously lacks a local pub that you can walk to. IMHO the closer you are to the hotel/ Swords Rd, the better.