PCSX2 can display only those games correctly that the developers spent time with.
RE4, Tekken5, FFX2, Street Fighter, etc. are displayed perfectly.
Games like Black and others on which they haven't worked won't work well.
Though they've only been working on getting games to display correctly, so don't expect good speeds.
Once they start working on speeding up the optimizations, you can expect it to become as perfect as PS1 emulation.
It's a really small group of people working on it in their free time.
If there were actual money and a whole lot of people involved, we would already be playing PS2 games on pc's years ago.
Until then enjoy the already perfected DC emulation.
