I must say, I was a tad disappointed in the Tower Pack. It sounded kind of cool on paper, but once in game it was rather meh. Although I am a HUGE Metro series fan, I will call things as I see them. Now, on to the developer pack.
First - the Museum. It's actually kind of cool, and here's why. In game when you are trying to survive you really have no time to stop and take a good look at the enemies trying to kill you. The museum is neat because up close you can look at every mutant\human in the game along with all of their movements. I like it because it really makes you appreciate the work these guys put into the models and animation. Truly stunning stuff here! I especially like how some of the mutants walk and run - the mechanics are amazing.
Next, the shooting gallery. This is cool because you can play around with ANY weapon in the game, even those that didn't appear in last light. (However the RPK is absent? Unless I missed something?)
You can select any weapon, customize it, and there are 10 levels of challenges against targets, dummies and "undead". The "undead" soldiers look like a cross between terminators and a character from Killzone. The challenges are pretty easy, and you can blow through them in 15 - 20 minutes or so, depending on what weapons you use. Again, this was fun and it was great to play with weapons that weren't even part of the LL campaign! (I won't spoil any surprises)
Next is the arena. You can pit humans against mutants, humans against humans, etc. The AI just goes at it for a while and you can watch from above each enemies fighting characteristics. It's so so, but a nice addition. The best part is this area has another 10 challenges! You get locked on the main battle floor and each challenge is a new mixture of humans and mutants. The first few are easy - kill 30 enemies comprised of unarmored humans and a few watchmen. However, as you can imagine this gets pretty crazy really fast! For example, by the time you get to level 8 you have to kill a total of 55 humans, mostly armored and some are heavies, PLUS the giant swamp creature which respawns after each time you kill it. Some strategy is involved here - for example I found it easier to avoid the swamp creature and focus on killing humans to try and get to 55. For whatever reason this is WAY more fun than the tower pack, although it sounds similar.
One thing I want to add about the arena - there's a switch to turn on\off a day\night cycle. I'm not joking when I say I must have just stood in the middle of the arena and watched the day night cycle 3 or 4 times. The way it casts shadows on everything as the sun moves, to the clouds that move outside - it's breathtaking if you are a graphics guy. It's one of the finest examples if not THE finest example of a day\night cycle I have seen. 4A, you rock!
Admittedly I have yet to do the single player mission. I'd love to dive into it tonight but this week is really busy with work and quite frankly I'd rather wait until the weekend when I have less on my mind so I can sit back Friday night and enjoy it.
I speculated before, but after playing this I would have to say that 4A are taking new ideas and technologies and putting them in the DLC to see what works, what's popular, and what did people enjoy. I wouldn't be surprised one bit if they are already knee deep in the next Metro game development, and they are testing the waters here.
1.) Faction Pack - the ranger mission - seeing how the community responds to level design that has no direct objective, multiple paths to completion, and exploration based. (huge hit I might add)
2.) Day\Night cycle - again, it's fantastic and my guess would be the next Metro game will have much more outdoor, open environments where a lot of time is spent and this could be put to serious use.
3.) "Undead" soldiers - pretty awesome looking, and definitely not "zombie" type models that have been done to death.
4.) Tower Pack - testing for future multiplayer Metro game? I believe they confirmed they plan on making one to release next year.
IDK, maybe I'm just reaching, but it makes sense I think!
Bottom line: Even if the single player mission is short, this pack is worth the money if you don't have the season pass.