no offence intended but its a golf gti (hothatch) who wants to spend there money on silly stuff like cruise control and parking sensors etc stop being so lazy and learn to park and just push the accelorator lol and spend your cash on good stuff ie re-maps etc etc 
I reverse into my garage, which would be much easier with parking sensors. I also reverse into my sisters driveway whenever I pop round, or have to parallel park when visiting my parents etc.
Parking sensors would make things much easier for me, although seem silly to others. I would rather spend on an accessory which will help protect my car, while making things much easier and convenient for me.
For £250 I think its well worth it for me and my needs.