I say that because I like the fact that PCem accurately emulates the speed of the IBM PC. It also uses the actual BIOS from different motherboard of the era. It will emulate everything from the original IBM PC to an AMI BIOS with a 486DX4/100.
There's some drawbacks, no internet capability, no serial/parallel emulation. So there's some limitations. However the good thing is for any game you might have you can expect it run like the real deal and not have to deal with the speed issues that you get with Virtual Box (despite they are making attempts at speed control).
So if you're a retro gamer this is for you. Certainly better than buying risky old machines off of eBay that hopefully work..