The Q50 is the best looking car in it's class. Period. Stay away from the chrome-on-black would be my only gripe.
I see a lot of complaints from car magazines/website about the interiror, mainly the split screen head unit. The interiror is beautiful, comfortable and funcitonal. If anything it's missing an extra drink holder or some storage space but it's a small car so not a lot of room to put these. The seats are excellent for long road trips.
Compared to other in its class it blows their doors off for thousands less. Most notable is you can get a base (Luxe) version of a Q50 and with little additional investment can get the same or better power that the Q50 Red Sport trim. The modding community is strong in this one.
The AWD is the way to go for best performance of this car. I've driven bot the RWD and AWD and it's a differnt/better car with AWD. My gripe here is the suspension is a little soft yet can be a little harsh over bumpy roads. It also has noticeable road noice at higher speeds over coarse/broken pavement. Some better coilovers and sound deadening would really help here.
I only put 13,500 miles or so on it in two years. Had zero issues with it other than serpentine belt & pully replaced under warranty as it was making noise.