Classics collide in a Windows 95 formatted, buggy mess. The action shall redeem itself.
Each game plays well though. There are no removed levels or content really. The Windows 95 launcher allows you to jump to any level that you can think of. If you have a custom .wad file available, then you can browse your computer to load and play it. The improved resolution can help not only to make it a more immersing experience, but it makes things look better. The audio is intact here, especially with the superb music found in the original Doom, and in both episodes of Final Doom. Do not worry about removed secrets that have been encountered in many other versions of Doom; they are all found here. If you want a version of Doom that plays a little like the newer FPS games, especially with free looking, higher polygon counts, jumping, a console, and other features, then you should enhance this game by acquiring jDoom, a converter that allows you to play the game with enhanced features and visuals. This collection doesn't really offer any of those, but that is perfectly reasonable, as jDoom is not an Id Software product, and the said converter totally improves the game beyond what Id wanted perhaps.
Conclusively speaking, if you want a total experience with the classics, then you should either convert what you have in this collection, or avoid it completely and track down the classics so that you have no bugs or full mouse support. However, this collection offers a lot for the price, and you may not find yourself removing the game either, as it takes up a very modest 85 megabytes of hard disk space. If you can tolerate or work around the mess-ups of the versions of Doom that you find in this collection, then you may as well forget about the original versions.