I have a 2012 vw GTI and I'm pretty happy with it so far. The interiors of the GTI are far superior to the regular Jettas. Soft touch materials everywhere and chrome accents in all the right places. There are no reliability issues to watch out for with the mk6 gtis that I know of.
Some data points for you (personal opinion/experience of course).
- decent gas mileage. (caveat, I have the DSG) I've been getting 25-27mpg this summer with AC on all the time. I also do lots of city driving and have a lead foot. Liberal usage of sport mode when I get the chance. 30+mpg is easily obtainable if you're on the highway a lot.
- I got the 4dr. Plenty of space in the back for adults. I'm about 6' and the person sitting behind me still has room. The hatchback is also super convenient if you ever need to move cargo. You can fit a suprising amount of crap back there with the seats down. Also super easy to park since the car is a bit short.
- I love the steering/handling. I especially love the steering wheel. LOVE. Seriously, go test drive one.
- seats are nice. Good amount of bolstering. Supposedly not that comfortable if you have thick thighs (or are a big dude), but i'm about normal sized and they're nice and comfy for me. Not everyone likes the plaid, but I think it looks nice.
- enough power. Probably the weakest of the hot hatch segment(ms3/st/wrx), but more than enough oomph for a bit of fun. I guess the benefit is better mileage and low torque steer. If you really need more power you can get a $500 stage 1 tune.
- sport suspension + low profile tires means it's a bit rough in the Chicago potholes, but I've taken a few long roadtrips and it's been perfectly comfortable. Plenty fine for a daily driver.