Wow that's an open ended question!
You will find that people who own Calibers have lots of things they love
and lots of things they would change-it's a first model year vehicle
bound to happen .
I personally bought a black SXT with cruise(speed) control and the security
package(alarm,micron filter and tonneau cover) with steel wheels.
It has 2.0L with CVT auto and standard sound system,have had windows
tinted and front headrests upholstered.
I drove it aggressively for the first 1000 kilometers,I have not experienced
any of the minor complaints that some people have(engine ping,exhaust
system noises and rear window washer leaking) and now at almost 3000
kilometers I consistently get 29 mpg city and 39 mpg highway(that's
to the imperial gallon here in Canada) right on the EPA estimates.
I put convex spot mirrors on the sideviews to make sure I had blindspts
taken care of and that works well for me at 6ft2in 225 lbs I have no problems
with comfort or driving as it's very comfortable on long drives.
Having said all that I love driving the Caliber and once you get by the
strange feeling of driving the CVT tranny(it takes a while) I am more than
satisfied with my purchase and yes there is room for improvement in some
Good luck on purchase what ever you buy.