Duke meets Medal of Honor. Duke Army really is a total conversion: not counting a few Duke one-liners pretty much everything in Duke Army is new (well, borrowed, textures from Half-Life and so on). Note that since this one utilizes high resolution textures and models an average Duke3D gaming rig pretty surely won't do. Also note that you need to get a relatively new version of EDuke32.
The TC was built with multiplayer in mind. This review focuses on the single-player campaign which sadly isn't that good. While I enjoyed the high resolution textures, the good looking models and some of the new gameplay mechanics Duke Army is essentially a very irritating conversion. There are five levels. Already the first one is a tough one. Dying instantly of enemy fire is not uncommon and usually you have no idea where the fire is coming from (the enemies are pretty quiet). If you get wounded there's nothing you can do about it except load game. Since this is essentially the same as dying I don't see what's the point (could be fun in multiplayer though). There are a few good moments however, for example, in the second level where you need to repel an invasion for a few minutes.
And while visually Duke Army looks very attractive it doesn't sound that good. Weapons sound fine but the environment is either quiet or occupied by never-ending explosions. Midis don't fit the maps at all so you better turn music off altogether. The pack has a test map with a tank, a choppa and a jet. You can fly around a bit, at least no one has done this before in Duke3D.
Conclusion: I have no idea how this works in multiplayer. It certainly seems interesting with its arsenal of new weapons and features but the single-player campaign is deeply flawed. You may want to take a look at it out of curiosity.