I knew a friend who did hardcore gaming on them. It is all a balancing act of what you want etc. I mean if you don't have the skills to install your own video card, etc into an Emachine and you want to play nice games then no they aren't going to be for you.
I can't say they suck overall cause honestly they don't. I would say they are no worse than say a dell with the same specs.
OP really needs to talk more about what they want the computer to do before advice can be given. Browsing internets and watching porn? Yeah an emachine will be fine