If aliens landed on Earth what impressions would they get about our planet?

What would impress the aliens the most would be the immense and diverse beauty of nature, and the various forms of art, such as painting, sculpture, architecture, music, dance, and literature. They would be as awestruck at these things as we are as natives.

Football, especially if they came in 1966.

(Don't let Walter tell you otherwise.)

I guess is depends on how they perceive the universe around them. If they are primarily smell driven, they would have no appreciation for our majestic vistas, but might really love the scents in a field in bloom. If they "see" in a different wavelength range, they might see beauty in things we completely miss and see nothing special in things that blow us away.

Definitely this. Here on earth, bees (for example), can see UV light. Flowers have all sorts of landing strip markings that we can't see, but they can.

I think aliens would also see our technology and wonder why we're so bogged down with picayune issues and why our priorities can often seem to be so messed up.

Here, I am specifically speaking about aliens with FTL travel or teleportation or even suspended animation, so they're far ahead of us in terms of inventions and other advances. They may wonder why we've only had a dozen of our species even walk on our satellite, let alone anyone try to terraform it or Mars. I think they would also wonder why we go to war so often (and sometimes on rather flimsy pretexts), or have a dozen types of toothpaste but no cures for some of our worst diseases.

I believe they would love everything about Earth not connected to humans. Humans I believe they would be frightened of.

Well, that would make them smart.

From Red Dwarf, (from memory.)

Lister: But they're aliens, everything about them is alien. Your broken leg could just be a form of communication.

Rimmer: How?

Lister: Well, it was below the knee and hurt like Hell. Hell....low. hello.

Cat: I don't wanna be around when one of these guys is giving a speech.

smeg!

They'd likely get the impression that the quality and beauty of natural processes here does not take priority over capital interests; that even natural processes are subject to capital interests when they hinder its progress. Aliens would see that this world has been run as a business, and that the health of humans and the planet has taken a backseat to the pursuit of capital.

They'd likely get the impression that humans of a particular location are expendable while others are not. They'd likely see the insanity of it all, and then leave before being even more disgusted?

I believe there is life out there. The fact that it doesn't visit Earth proves it is intelligent.

... boiled, fried, fricasseed, broiled, sauteed, baked, ....