izigame.me

You don't need me to give you a review. This game hasn't left my hard drive in 30 years. The legacy of Doom II precedes it in that the fan community not only still exists, but is still making content for this game to this day. What you do want to hear is is it worth buying this version?
Of course it is.
You get the new Unity version, which is a little more accessible for most players. Runs on modern systems smoothly, has controller support, a couple quality of life upgrades, and built-in access to a curated list of several additions to the game - including official ones such as Final Doom and Master Levels, but also some fan projects such as Back to Saturn X and Harmony. It is the perfect entry point for anyone who's never played this classic before, even with the unfortunately necessary censorship of a few textures (though a much better job of it than the BFG edition).
However, you also get the original, DOS versions of not only Doom II, but Final Doom and the Master Levels. These are the original, uncensored released, with the .wad (game data) files available for use with various source ports. And that is where Doom II truly shines today.
The Doom community has created thousands of custom levels, hundreds of mods, various source ports and engine upgrades. All you need to do is provide them with the base data files, that you have included in this pack. This is more geared for advanced users, who know their way around the file system. And these can open up the doors to a whole new world of experiences. My suggestion is to learn how to use these custom tools, and you'll have a nearly endless supply of content available to you. I cannot help you with this part, there are guides online for how to install and use the source ports.
Doom II is far more than just a game. And the price of entry into this whole world of content is one of the best values on Steam.