Played through it with 2 friends of mine, going Wizard/Paladin, Warlock, and Ranger (Started as a Wizard, and changed to a Paladin for the 2nd attempt). Like you said, it become much simpler once you know what's going on and what to expect. The level was fun, however as someone who's never played doom, and had no idea what the level being recreated was, there were parts of it that definitely seemed pointless, or just out of place. For example, there were all of those upgrades lying about, and although they may have been beneficial, they seemed pointless, as there was no build up through the level. At the end there was just a Skeletal Knight mini-boss, which I ran past to the exit for the win. Having so many lives to start off with (It seemed like 5 per player) meant the playstyle was essentially throw ourselves at problems until we overcame them, and the abundance of food also took away from the feeling of anxiety. That being said, the food was entirely necessary, because by the end we had eaten every piece of it, and were low on lives.
The use of invulnerability potions were interesting, and enjoyable, however since it gave extras so many extras (1 for each player in the bottom room, plus one more at the end of the acid water), when you only needed the one potion to get the key, and the other potion and get out, it essentially allowed for abuse of the potions. In my personal opinion, this is just a fault with invulnerability potions, as they are immensely broken in the normal campaign as well.
The secrets in the level were also lacking, for a game that seemingly was focused on finding these secrets. My group found them all, but I honestly never felt like I found a single one. It's possible that I didn't, and my friends found them all, and didn't announce it, but there was nothing secret feeling about anything I encountered / opened.
Like I said at the beginning, it was fun, but these are just a few point that I feel could be improved upon.
(Also, just as an over-all thing, the scripting could stand being cleaned up a bit, such as not requiring everyone to teleport, not requiring everyone to be present to win, providing excess potions, even when only one person is playing, and so on)