Having just seen Lord of The Rings : The Two Towers today I'd really recommend it. It's nearly 3 hours long and not a minute of screen time is wasted.
It's awesome in it's scope, the battle scenes are unbelievable, the photography is out of this world and, yes, there's even touches of humour in it.
It's a much more 'rounded' film than The Fellowship of the Ring (which I was also completely gobsmacked by!) and it lets you see more of the character of the main protagonists.
If you loved the first film, this second one will completely blow you away.
BTW - did I say I really liked it?????