Laser teeth whitening - is it any good?

Would appreciate information from anyone who's had it done or is knowledgeable on the subject. Is it painful, does it last, any side-affects, etc.?
--------------------
Its not painfull but your teeth will be sensitive for a while afterwards, the results vary depending if you smoke, eat alot of stuff with food colouring, eg red wine curries etc, these shouldn't be eaten for a while afterwards as the bleaching causes the surface of your teeth to become porous, you would probably get the same result with the home bleaching kit its less expensive and you just put the trays in overnight for a while, the laser bleaching will cost you more but is less hassle and your teeth should lighten by up to 9 shades and has immediate results
Source