So high a rate in many platforms already tells a lot about this masterpiece.
The main characteristic that sets apart this show from others of similar genre is its uniqueness: a lot of dark humor, alcoholism, catchy phrases, a down-to-earth character called Mr Poopy Butthole and fascinating scientific concepts all in the same place.
Who in the whole Multiverse can do anything he wants, only when he wants? The answer is clear: Rick Sanchez — Wubba lubba dub dub!
The only drawback I could think about right now is its animation: it's not bad; it's not, however, good either.
I strongly recommend you watch Rick and Morty — especially those episodes that carry a deep philosophical meaning — like the one (Morty night run) wherein Morty successfully saves a prisoner from being assassinated. In the process of helping it escape the "galactic police," he sacrifices uncountable lives of many inteligent beings. however, in the end, he ends up killing the jailbreaker as he finds out it's horrible secret.