Whether it's worth fixing depends what you want to use it for. If it's for just riding around town, maybe - but not if you want to use it as a bike for anything much more than that. It won't be a nice ride, and it will cost only a bit more to get a decent frame as a starting point, if you want to build your own bike up
Plus getting parts to work with those chainrings is probably going to be more trouble that it's worth, so I'd remove that for starters...