Steve Corey posted some news about the port of Doom on the Wii:

There's been a few questions about FreeDoom, what it is, and why it was included, so I wanted to clear up a few things:

The original Doom levels are STILL commercial, so they're not free. While I CAN have free reign over the engine, I cannot include the levels. That is one of the reasons someone started the FreeDOOM project. It is independent of id Software, and is NOT an official Doom version. If you have the commercial Doom levels (Doom, Doom II, Ultimate Doom, Final Doom), you can use that instead. I just didn't want to put out WiiDoom without having an option for people who don't own Doom levels.

To me, it doesn't get any better than the original levels, and that's what I play.