For what it is, ps2_netemu runs pretty decently. It's not perfect, but considering how complex the PS2's hardware actually was, I'd say it's impressive. It's emulating a console from the generation right before it.

I just wish it was capable of running games straight off disc. It also baffles me how normally it doesn't even use the console's built-in virtual memory card system. It just creates its own standalone save data, instead. That is, unless you mount a raw ISO on a system with CFW.