Okay, let me start this review out by saying this: Steam royally screwed up what could have ben an awesome product. There is just not enough reason to justify this purchase when it is the bare minimum of what could have been done to make this a working game. The Commander Keen series is an amazing set of games, a piece of the history of PC gaming, and Steam treated this piece of history like most people treat their garbage.
To elaborate, Commander Keen was the first PC game to have Parallax scrolling, the same kind of scrolling that Super Mario uses to be able to have a Platformer. At the time, it was a huge deal to have the entire level not be a single screen. So Commander Keen was produced to prove that a PC could support a full Platformer of many screens and levels. The game has an overworld and lets you play levels in any order, you get to shoot enemies from a distant and it is also the Nintendo Hard you would expect from a classic game, so it should be a dream for people who wish to visit a time when 2D was king. To neglect this classic trilogy and the 2/3rds of a trilogy sequel would be a shame.
Now, I am not suggesting you buy this pack. Especially if you don't know the series already. This pack is a bare minimum attempt at a quick buck off of some old shareware games. Yes, you heard me, SHAREWARE. If you are not aware, due to age or not being a PC gamer until after Floppy Disks disappeared, Shareware was the precursor to Playable Demo games on services such as Playstation Network, X-Box Live Arcade and yes, even Steam, where you would get a part of the game on a floppy disk at no charge, to try out. In the main menu, you would often see an "Order Now!" or "Ordering Details" option that let you buy the full game's disk for a reasonable sum of money. It spread the word of companies and got them some revenue as well as positive customer feedback that people were willing to pay money for their ideas.
So, since the game (well Commander Keen 1 and Commander Keen 4 are Shareware, at least) is technically free, you would think that this pack would do something more to make you want to buy it, right? Well, you'd be wrong. In fact, this pack is actually more of a hassle than going out and downloading Commander Keen 1, 2, 3 and 4 and a DOSBox Emulator yourself. To access any game past Commander Keen 1, you have to open up your Steam window, go into your library and launch it from there. Double Clicking the Shortcut that is generated on the desktop does nothing more than launch the first game. Not even a hastily slapped together Commander Keen selection menu screen comes up, just the default steam menu with radial buttions even after going through the hassle.
So I suggest to you to save your money, go get a DOSBox Emulator, and download Commander Keen 1 to try out. You don't have to send any money and it is legal because that's how the game was released back in the day. And if you go and get the non-shareware games? Well, it's not like ID software is going to come after you for picking up a title that they don't even have the rights to anymore. Though, the one thing this pack does RIGHT is that Commander Keen 5: The Armageddon Machine has it's copy protection (having one of the items you need to complete the level not spawn at all, making the second level impossible to complete) set to working properly as if you bought the game.