24 is a game that I'd expect to have for a month or less and then be done with it (like BDK). However, it's been in my collection for several months now and I'm still having fun with it. It is a game that seems simple on the surface level, but once you dig deeper into the rules and the nuances of them, it becomes a much more rewarding experience. The subtleties that surely most gloss over actually make a pretty large difference in scoring, and that's where this game shines.
Initially the game is confusing, and that's due to there being little indication of what things do on the playfield except for the obvious callouts along the lines of, "Shoot the Suitcase to start multiball". It took me a while to adjust to the fact that a mode is always running (that's what the 24 lights are for), and it took a while to figure out I was making progress in any modes or even figuring out what part of multiball I was in. That aside, once you put a bunch of games on the machine and start connecting the dots, the game becomes much more comfortable to play since you actually have an idea of how you are progressing through the game.
The game also has four main multiball modes (a fifth if you count the wizard mode, "Master Agent"). The only issue with these is that you are only going to be starting two frequently--Suitcase (the majority of the time), and the Scene 6 multiball. The other two, Sniper and Safe House, depending on settings may be easily accessible in the beginning of a game, but they eventually become prohibitive as you play longer. As such the game can become boring fairly quickly since you will be playing a lot of Suitcase multiball. However, that's where the nuances of the game come into play. Sure, you can play Suitcase over and over all day on its own, or you can use it to build on other things.
The game can feel boring when you are simply playing Suitcase over and over, however, it can also feel highly rewarding if you play to fill in all the blocks on the playfield to get to "Master Agent". The thing is, it's not easy to do this. Getting the Safe House Jackpot, Nuke Jackpot, and Sniper Jackpot all require work, especially the Sniper one, and getting to the end wizard mode is going to require serious planning (cascading multiball into multiball, and taking advantage of the add-a-ball on the Super collect). Casual players likely will never see Master Agent, but players that really like to dig into a game and plan things out and work towards higher goals will find it fun and satisfying overall.
For the casual player, there is a mini wizard mode dubbed "Save the President". It is a tense single-ball mode where every shot must be hit, some twice each. The points can be decently sized and the end collect shot feels satisfying. All it takes is starting the multiballs for Safe House, Suitcase and Sniper to get to it, so this is something lesser skilled players will at least be able to see.
As far as subtleties, one of my favorite aspects about the game is the MOLE multiplier. Completing the MOLE targets lights a hurry-up on the left ramp, and collecting this awards you a multiplier on one of the main shots (orbits, Safe House, Suitcase, or Sniper shots). The thing is, what it awards you is completely random. Also, you can keep collecting MOLE hurry-ups and the multipliers can build on the same shots even higher--up to 5X. The biggest thing with this however is that the multipliers don't go away when you drain like they do in other Stern games--they stay for the entire game, so progressing your multipliers can absolutely make or break a potentially high scoring game. Getting these multipliers up adds more depth to the game as well and forces you to change your priorities. Do I keep hitting the center ramp when in suitcase to build my Super, or do I milk the orbits I've got multiplied at 4X instead? Obviously, I'm going to take the left orbit. There is a lot of fun to be had with trying to get your MOLE multipliers up as high as you can.
Sound-wise, I hear a lot of people complain about the Chloe voiceover. Personally it never bothered me, but I can see where some people might get annoyed. Music-wise I really dig the soundtrack to the game. It's got that techno-rock kind of vibe that you hear in games like Spider Man or Batman: Dark Knight, but it fits the fast flow of the game very well. The sound effects asides from the Chloe voice are excellent, and they go with the DMD animations very well (especially the Safe House one where the house explodes).
Overall I really enjoy 24. I think it's a bit of an underrated Stern game, and beats out games like Avatar, BDK, and probably a lot of their earlier stuff. It's a good flow game, it's fun for beginners, but it's got enough subtlety there to be enjoyable for higher level players as well. It's a bit of a rare machine all things considered, so if you see it, I highly recommend giving it a try.