Faults:

Stock tires wore out at 26k miles, but see below for details.

General Comments:

To elaborate on the stock tires above: this car lends itself to very spirited driving and I am far from a lead foot. The car's sporty suspension handles so well that you will find yourself taking turns harder :) So I happily take responsibility for the tires wearing out so quickly (and I'm getting ready to replace them again, haha).

There was a voluntary safety notice on the power steering fluid (?) and my dealer was able to get me in and fixed relatively quickly.

Definitely opt for the 2.3L if you can. It's hard to believe this car is in the same category as the anemic Civic and Corollas.

The auto transmission comes with a "manu-matic" mode, which is fun but I don't use it very much.

It has a very deep glove box. More like a boot box.

The interior is high quality, doesn't feel like you're in an econobox. Except for some slight tearing on my steering wheel, the interior has worn and aged really well. While I opted for the base model, it still comes standard with an aux jack and ambient temperature on the radio display (which can be hacked to show fuel stats like average/current MPG and remaining distance).

Rear seating is a bit cramped. I would not recommend putting anybody over 5'2" back there.

Hatchback is very spacious and convenient for toting things.

Not a lot of safety features on the base model, but you can get side airbags on the next trim up.

Faults:

Coolant leak in early 2012, bad gasket at engine, repair cost roughly $250 mostly labor, including refill with new coolant.

Check engine light came on in 2009, covered by warranty, PCV not working properly, components replaced (would have cost several hundred out of pocket, so very good that the warranty covered it).

General Comments:

The 2007 Mazda 3 is a high quality Japanese vehicle (made in Japan), built on a frame engineered by Volvo.

It provides wonderful cornering, with a firm European style ride. The firm ride is something I like, having previously owned a Volvo and a VW. But if you prefer the cushy ride common in American nameplate autos, you may find the experience a bit rough.

The 2.0 engine I have is a great size for this vehicle. It provides very good fuel economy (mid 20s in city, mid 30s on highway) along with more than enough - but not exceptional - power. The power is better than you'll find in most econoboxes.

The automatic transmission is Tiptronic, meaning you can if you prefer choose to select the gear you are in. I quite like this feature - I use it nearly all the time.

This compact is as large as you can get and still be considered a compact. Despite this, the trunk is slightly small versus some of the competition. The driver's seat and front passenger seat are very comfortable, the driver's seat especially has many adjustment options. The rear seating is better than many compacts, but an adult or even teenager sitting back there will not forget they are in a compact.

I have the black-based interior, which is aesthetically very pleasing IMO. The glove compartment is HUGE.

The keyfob does not include a trunk release, which is a pain.

Not all models come with side airbags and anti-lock brakes. If you are very concerned about safety, make sure you check out if the car you're interested in has these features.

Faults:

Major - Rear suspension control arm bushings (clunk from rear over bumps).

Minor - timing cover oil leak (warranty covered) - leak on the back of the engine facing firewall.

Minor - intake manifold cold tick (warranty covered) - still ticking after replacement, so I am living with it.

Major - Clunk on the left side over small bumps - turned out to be transmission mount centre bolt loose - appears to be the same issue that plagued the Mazdaspeed 3 (turbo 2.3) - tightened myself to 80 ft-lbs (look at the articles describing how to do the Mazdaspeed/turbo 2007 cars, and then the service manual for the correct torque).

Minor - Belt noise (hissing especially when cold) - just replace the belts to fix - 'gurgling' noise at 1500 RPM warm - replaced drive belt tensioner (there is a 1500 RPM noise when cold - haven't found what is causing that yet - I think it is the EGR).

Minor - rear brakes dragging due to corrosion in the rear caliper guides (pushing rubber guide boots against slide pins, binding rear brakes) - just ream corrosion out.

Major - driver side front strut had a 1 inch "dead zone", where there was no damping - seemed to ride OK - noticed it after upgrading the front struts.

Minor - Aluminum shavings in drain oil - turned out to be from galling threads on the drain plug - a Fumoto valve fixed that.

Minor - metallic click noise when shifting from park to Drive, or Drive to reverse - apply grease between driveshaft and hub bearing mating surface - as per TSB (dealer told me about this)

Minor - 17 inch alloy rims seem to dent easily (inner face - from potholes) - have had to get all 4 corrected at a rim repair place to correct vibration.

Minor - front brake replacement - changed back to OEM when the fronts were pulsing from aftermarket discs/brakes. Note that the front discs will rust onto the outer ridge of the wheel hub - search online for tricks to remove (removed mine in 30 minutes by using the rotor removal trick used by Ford F150 people - putting bolts in the caliper mounting holes to apply force to the rotor and pop the rotor off).

General Comments:

As others have said - great low end torque from a 4 cylinder - really adds to driving experience. Handles very well (a little harsh/sporty - you hear/feel the road).

Good comfort - does 4 hour road trips comfortably. Seats support well. Even the rear seats are comfortable. Quiet interior, apart from road/engine noise. Heating/cooling is sufficient (note that many after market cabin air filters do not have the correction to them to allow the AC to work better - a baffle attached to the filter itself - so aftermarket cabin air filters may reduce AC effectiveness).

Fit/finish on mine seems very good/solid.

Mileage seems OK - a mixed rating of 10L/100km (but I have a heavy accelerator foot).

Unlike some, I find it is OK in the snow with good snow tires. ABS helps, but it is a low vehicle with wide tires - it won't be amazing in the snow. Summer is when this car performs well.