These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
For Battlefield 2: Strike At Karkand. Infantry Only Mode.
Strike at Karkand is so popular that it was brought back for Battlefield 2142 and Battlefield 3!
For the franchise as a whole: Wake Island. It's in Battlefield 1942, Battlefield Vietnam, Battlefield 2, Battlefield 2142, Battlefield 1943, Battlefield Heroes, and Battlefield 3. That's almost the entire series!
Even Better Sequel: Battlefield 2 was this compared to Battlefield 1942, and still seen by many as the high point of the series. Any future Battlefield will at some point be compared to BF2, with similarities often seen as a positive thing.
Game Breaker: Numerous examples throughout the series, including Vietnam's M60 / LAW kit, BF2's dolphin diving, the post-boost pre-nerf RPD, Bad Companies M60 toting medic class, the one-way portable walls the Sniper carried in 2142, anything involving China on Wake or the US on Karkand, and attack helicopters that can survive a direct hit from the main gun of an Abrams, Jets in both Modern Battlefield games, and in many people's opinion, the Voss / PK rocket combo in 2142.
Good Bad Bugs: Several. One amusing one was that in 2, the round would end with a stock view of the Battlefield. Since none of the players were controlling their (now-invincible) vehicles, this could lead to some amusing sights, like a cartwheeling fighter-bomber.
This bug was apparently popular enough to be kept in Battlefield Heroes, which is based on the Battlefield 2 engine.
Another one, that could be considered a glitch in 2, is when a person would go prone right next to a wall or a fence. The game would allow the model to go through if the person was right next to the wall, allowing another player to shoot (or knife) the protruding body part.
Internet Backdraft: The announcement that 2142 would have mandatory online advertising displayed in the game did not get a good reaction from gamers. Compared to some of the Copy Protection methods employed by certain modern-day games (or even a number of contemporary games released on Steam), though, the advertising in 2142 now looks downright tame.
Memetic Mutation: The classic BF2 habit of yelling "enemy boat spotted" repeatedly on a map with no water.
This goes as far back as BF1942, in which people often spotted submarines on desert maps.
Sophomore Slump: Battlefield: Vietnam was the lowest-selling Battlefield title to date, and is generally regarded as the worst game in the series. Numerous Competitive Balance problems didn't help.
Stop Helping Me!: Battlefield 2's revive ability for the medics. Some players would revive at bad times, such as when a person is trying to respawn with a different class, or at a more important location.
Medics often revive in the middle of a firefight, run away and leave you for death. Then they revive you again, ignoring all the enemies around and it goes on and on and on. Especially infuriating if there are snipers around. Particularly maddening when the medic and your killer are working together to pad their stats.
Unfortunate Implications: In Battlefield 2, the American Assault, Support, and Anti-Tank class models are African American. They are also the three classes that have body armor, the classes that are considered to have "simpler" roles, and the ones expected to take lots of bullets...