Currently have a 2011 Leon FR which I have had from new (june '11) and now has 49k miles and it has been absolutely faultless.
But prior to that I had a MK5 Golf GT Sport 170ps and have to say I much preferred that in comparison, covered 80k miles in that in the 2 years I had it.
The Golf had a much punchier engine which was the nature of the old pd engines, where as the new CR engines have a much more linear power curve which makes the performance feel a bit flat sadly. Can't say there is any noticeable difference in mpg between the two.
I also felt my Golf was more fun to hustle through the bends with less body roll, just felt vey connected to the road where as the Leon has more body roll and less initial turn in.
Lastly I have to admit the Leon is already starting to feel a bit loose at only 19months old, just isn't wearing particularly well and the front bumper really needs spraying as its stone chipped to hell.
Not even worth comparing the Leon to our MK6 GTi as the Golf is in a completely different league and its easy to see where the extra money goes, was about £5k more for a Golf GTD of an equivalent spec when I ordered the FR.
If you can get it cheap enough the Leon is a great all rounder but IMO about 70% as god as an equivalent Golf.