A great, well-designed little car. Very comfortable for me (I'm 6'2", 220#) with more headroom than my Dad's minivan and more knee room than my friend's Mazda 3. As a tall person who usually finds the steering wheel partially blocking the speedometer, I actually found the center-mount speedo an improvement. Have driven the car through Wyoming blizzards and ugly urban commutes and found it pleasant, sturdy and nimble. It also holds a lot, like me, my 2-man crew, 2 tool boxes, & 25 gallons of paint (never thought the Yaris would muscle in on my pick-up!). Best mileage I've had was 42mpg on a run between S.F. and Reno. The worst was 25 mpg in urban stop & go commuting (using no freeways at all).
Had no idea the car would be so much fun to drive. Super-responsive steering and quick acceleration in the 0-50mph range (much like a Mini or Jetta). The engine can dog a bit on sustained climbs at highways speeds, but nothing as bad as the Hyundais or Ford Focuses I've driven in similar conditions.
The main issue with the Yaris cockpit design is visibility--the A-pillars to the left and right of the windshield eat a lot of space, and frequently block the turn signals of vehicles around you in multi-lane environments like freeways. Can also create a blind spot for pedestrians in crosswalks.