This game is my first experience with the Ace Combat franchise, and I'm glad that it was this one, instead of the older titles. Well, I had an XBox 360 back then, so no other choices on that matter anyway.
Unlike the older titles, the graphics of 6 is beautiful, especially the aircraft and ordnance models, and more so for a game released back in 2007. It's set in Strangereal, the Ace Combat universe's version of Earth, with entirely different countries and continents, yet all aircraft and their ordnance are real-life, with the exception of the game's "super-aircraft". Ground and naval vehicles are also mostly real-life, with few exceptions.
The campaign is also unique in the series because each mission is divided into multiple "operations", except smaller missions, or missions where there is only one singular objective. A large mission can also advance to "no operations" stage once enough has been completed. By helping out with an operation, the friendly unit(s) involved is freed up, and can assist the player by providing extra firepower once the player's requested it. This makes it feels like there's an entire military force (which it is, the Emmerian military) backing you up, instead of just you doing everything. Not to mention, whenever they're called upon to provide extra firepower, the scene of them unleashing destruction on the enemy is just awesome.
Last but not least, as per Ace Combat tradition, the soundtrack is excellent. The main theme, Liberation of Gracemeria, is certainly one of the most beautiful and emotional themes ever. It manages to make you feel patriotic for a country that doesn't even exist. It's glorious.
Unless you pre-ordered Ace Combat 7 for XBox One, which gives you a copy of 6 that was ported to said console, or still having the OG 360 copy, there's no other way to play this game, and it's effectively lost media now. Until somehow the GOG team can make a miracle happen that is. One can only hope for the best.