I like Date class from Fuel, but it is not enough some features, as I see. Several useful features that exists in standard PHP class DateTime are may be very useful to add them into Fuel Date. Like this:
$startDate = new \Date('2015-08-01'); $endDate = new \Date('2015-08-31');
$offset = $startDate->diff($endDate); // this first
We wrote an entire new Date class, that was interface compatible with PHP's DateTime class (so you could also use it in any function or method that uses DateTimeInterface as a typehint. See https://github.com/fuelphp/common/blob/master/src/Date.php.
Which worked fine, until some moron decided that for PHP 5.5, your own classes may no longer implement DateTimeInterface, see https://twitter.com/WanWizard/status/565873929659887616. Was reported to PHP internals, but as usual, only silence...
So we're back to the drawing board on this one.
In the meantime, you can include fuelphp/common using composer, and use \FuelPHP\Common\Date in your projects, the code has been stable for a while. It has all DateTime features, plus the v1 Date methods like create_from_string(), etc.