First I want to greatly thank you for such an extensive review. The thoughts that you had about it (the good and the bad) are exactly what I need to try to make even better maps in the future. Thanks!

A note about that bridge (if you didn't do it already):
If you attempt to activate the button again it will tell you: Unauthorized bridge use detected. Bridge deactivated. Just another little extra for everyone.

The reason is mostly because of the monsters and weapon choices just like you said. And also, there are countless new entities in it that allow you to do so much more than you could ever do for the regular Half-Life. (At least significantly easier)

Another reason is because you have much more freedom with custom models. It is a lot more work making a single map with monsters/weapons with new models, and even then you can only have one type. For example in this Sven Coop level that you just played I have two diferent models (each with different damage rating even) and you can't do either of those things with HL.

Final reason is because it is a nice change of pace from the regular HL. New experiences, weapons, monsters, models, etc,... And it is kind of nice for a change being able to respawn after death and not have to reload and do the entire part over again. But this is not a problem though because I like my single player levels difficult.

I actually play through HL and Opposing Force on hard difficulty with an almost constant 100/100 health and armor the entire game.

Also Niborius I will send you a PM letting you know which Milestones you missed. (If you want to find them for yourself then just delete it)

Niborius, do you happen to remember when you got to the pit with all of the blood in it did you see all of the bodies? I noticed that sometimes you don't becuase they fade away, but other times they stay.