I'm pretty sure you would be a bit lost, and I'm betting the atmosphere of P2 builds on P1.
It is perfectly OK. Portal 2 has tutorials at the beginning (From what I've heard) so anyone can play it wihtout any prior knoweldge.
However if you want to optimise your gaming experience, you should play Portal 1 first!
If you have an nvidia game card, you can play a bit of portal 1 for free
Its a much cleaner enviroment to start with,