Will people like your game if it's ugly?

Dwarf Fortress, as mentioend in one of the comments, is a big counterexample. Other older ASCII art games that remain popular fall into this bin as well (NetHack, Rogue). Not to mention any of the popular Flash games with graphics somewhere in the range of minimal to shitty.

It is definitely much easier to draw people into playing your game if it looks nice/has a cool and cohesive aesthetic (the 6-second GIF heuristic mentioned in the top-comment), but if your game is a major success in other ways, it can be a hit despite what it looks like. But that doesn't mean you should neglect the aesthetics: part of getting something to be popular is removing as many of these "despites"/barriers-to-entry as possible.