Actually, criticize is a perfectly acceptable English spelling; it's not just the Americans who use it. The -ize suffix is perhaps more old-fashioned English than -ise but it's nothing that should be criticized.
If it's good enough for The Times, it's good enough for me.
If you're going to nit-pick about people's spelling, then there are plenty of more worthy targets on the internet!!
Cheers
Whirls