They're fine as daily drivers, so long as you keep on top of maintanance and you don't expect 40mpg when you thrash it. Economy on the motorway is excellent imo, i recently did 350 miles (mainly motorway 70-80ish, a bit of town) to 37 quid of petrol. Not bad if you ask me!
I've had a mk2 gti as a daily driver for the last 18 months now and apart from an alternator failure (could happen on any car) and a dodgy hall sender connection i've had no problems.