String concatenation vs. string formatting

[Andrew Berg]

Is it bad practice to use this
> logger.error(self.preset_file + ' could not be stored - ' +
> sys.exc_info()[1])
Instead of this?
> logger.error('{file} could not be stored -
> {error}'.format(file=self.preset_file, error=sys.exc_info()[1]))


Other than the case where a variable isn't a string (format() converts
variables to strings, automatically, right?) and when a variable is used
a bunch of times, concatenation is fine, but somehow, it seems wrong.
Sorry if this seems a bit silly, but I'm a novice when it comes to
design. Plus, there's not really supposed to be "more than one way to do
it" in Python.