Read what Derick things about this change being good for making PHP applications better:
I find it kind of amusing to observe a script language trying to become a real programing language. :p
It is indeed. ;)
http://derickrethans.nl/fanmail.php
Sure, if you are not going on this route, you can do so. But be warned that quite some Drupal developers are or at least try to be on the bleeding edge with actual software (to get bug fixes, use new features), so actually these core developers will not be able to use your code. Eg. last time it was asked, drupaldevs.org ran on PHP 5, JonBob, Killes and others having development spaces there.
Drupaldevs is down for several months now. :p
Which is not relevant, really :P I just wanted to point out that PHP 5 was used quite some time ago on this server, and I personally expect that other core developers (and high profile users, even among the PHP developers) will (try to) use Drupal with PHP 5. Goba