Apparently, Samuel 'Kaiser' Villarreal wasn't so happy with his and others' work on the older Doom 64 TC, Absolution, so he went ahead and coded a custom Doom Engine from scratch for emulating the physics of the 64 port as closely as possible. Even though there are still a few graphical glitches here and there, it looks like he accomplished what he had set out to do. Now it's possible to play Midway's Doom II sequel in its entirety in hi-res and with mouselook support. I didn't know that this game was much more than a port - it comes with it's own megawad and uses all new assets, i.e. new sprites, textures, sound, music and all. Starts off a little slow but progressively gets better. The most striking thing is that it has a very different atmosphere than the source game, mostly owing to a bleaker texture set, gloomy colored lighting and the ambient score. I'm halfway through the pack and enjoying it immensely. Definitely recommended.
Get the 'Kex Engine' at from Kaiser's website and find yourself a rom of Doom 64 (which is needed for creating an IWAD from):
http://doom64ex.wordpress.com
Oh, and don't worry about the screenshots on the Media page - you can toggle bilinear filtering off.