I'm a new owner of a 2009 Cobalt XFE sedan (manual) and am very happy with it for these first two weeks. I bought it used with 4K miles and got a great deal.
A little bit about me: I've driven mostly chevy's for the past 25 years and have been very pleased. I was particularly happy with an old chevette which lasted me 5 years and through college with no repairs (0.16$ per mile cost of total ownership). My next chevy, an S10, lasted me 13 years and never saw a mechanic (I did replace a water pump myself at 77k miles), and ran until I crashed it at 143k miles. For the past 6 years I've been driving a pontiac grand prix and really like it mostly (great cruising on highway) but with 206K miles and a 156 mile daily commute I thought it time to look for something else. I also own a 99 corvette and did not want to burn it up on my daily commute, and through the winter, so an economical vehicle fit the bill.
I'm still getting used to the new cobalt. I waxed it last weekend and am very pleased with the looks. I don't mind the interior at all (some say its cheap), or the seats (a little hard). My base model has no options at all, which takes a little getting used to (no key fob and hand crank windows), but no complaints.
Mileage expectations: I was hoping to achieve the 37mpg rating and am not sure yet whether I'll get that (first 3 fillups were 33,34, and 38 mpg). My chevette got me 33mpg with its carburated engine, my pontiac got me 30 mpg somehow even with a 3.1V6, and my corvette gets me 25mpg which is amazing considering its 5.7LV8.
The cobalt stock radio is pretty good, way better than the corvette and pontiac.
Ride: Very pleased with the ride on the highway. The road noise is very low, no problem. I was initially concerned with the gearing, requiring 2,500 rpm to go 65-70 mph, which seemed a bit high, but I can't even hear the engine and if the mileage is high I don't care about the rpms.
Handling: Pretty bad cornering, I may want to upgrade the struts/sway bars at 50k miles, but then again I don't want to drive it like my corvette and just need to get to/from work. No complaints, really.
Well that's about it.