The upvoting system is Reddit's greatest strength and their greatest weakness IMO.
There is value in the wisdom of the crowd. But for complex or nuanced topics the crowd is typically not willing to think that deeply, and they just ignore posts or down vote them because it doesn't fit their chosen side.
The interface sucks too though. And they try to spam you.
Also, there's no sense of community. Like here you have the same group of people, but every forum on Reddit feels like you're talking to people that you'll never hear from again.