Is fallout 3 first person shooter?

Answer 1

yes

In some sense yes- in some sense no.

It is an open world RPG to say the least- and follows on the same engine as oblivion.

So expect combat to be rough and tough.

Answer 2

It is First AND third person. To change to 3rd Person, you can press L-2 (PS3) or LT (Xbox 360).