Honestly? It kinda sucked. There wasn't anything "realistic" about it. Does it deserve it's B classification? Yes. Is it intelligent and entertaining? No. A realistic invasion would probably end up more like D-Day if they tried to take over the planet, and if they weren't trying to colonise the thing, they could probably just shatter the hting from orbitand pick up the pieces.

This is also assuming they went ot all the trouble to crossing multiple light years to select OUR planet for it's resources despite the abundance of said resources on pretty much every other object in the solar system (water, minerals, metals, etc). If anything, they would A) ignore us; we're not really that significant when it comes to interstellar travel, perhaps they would study us from afar for their alien college thesises, or B) attempt diplomatic relations. "Hey guys, we're aliens; yes we DO exist, and we've come to tell you to tone it down a bit, 'cause you're blowing the crap out of your planet, so why not be more nice and AUUUGH!! OUR SPACESHIP!! Screw you lot, we're leaving!"