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.
YMMV: Just Cause
Crazy Awesome: There might be a way to take over a country without car surfing, an infinite supply of parachutes, and a grappling hook gauntlet, but that's not Rico's way.
Crosses the Line Twice: How the game keeps you from taking it too seriously. A kangaroo court so efficient it can kill thirty people in an hour? Disturbing. President Panay bragging about it as propaganda and urging people to buy his book about it, titled Execution Extravaganza? Hilarious.
Crowning Music of Awesome: This little gem, which has a completely different feel from the rest of the game's Bond-style soundtrack, but just makes you want to go out and shoot people FOR THE GLORY OF PANAU.
Ear Worm: It may be somewhat generic as far as dance music goes, but the thumping music that plays constantly around the Mile High Club will stay in your head for days.
Good Bad Bugs: It's possible to steer some cars while standing on top of them.
There's an achievement for driving all unique vehicles on Panau. DLC vehicles do not increase the amount of vehicles you need to drive, but driving one does add towards the total. Not very useful on its own, but when you're missing just one vehicle...
"Funny Aneurysm" Moment: Foreign powers are posturing and nearly fighting over undersea oil deposits. Wait, are we talking about Panau or the South China Sea?
Ho Yay: It's hard not to suspect Sri Irawan may have some special feelings for Rico.
Most Wonderful Sound: When you complete a base capture mission, the Mooks you've been escorting start chanting "SCORPIO! SCORPIO! SCORPIO!". It serves the dual function of letting you know that the worst is now over and making you feel like the biggest Bad Ass on the planet.
"Real Americans hate commies." (cutscene ends abruptly)
Polished Port: Just Cause 2's PC release is quite well optimized, running much more smoothly than most Wide Open Sandbox games released this generation in spite of its massive scale while continuing to look really good, and the keyboard and mouse controls are responsive and customizable. Other developers could learn a thing or two about porting games to the PC from Avalanche Studios.
Then there's the fan-made multiplayer mod, which has finally been released on Steam after numerous beta tests. Hell, even if you were to ignore the multiplayer mod, the game's surprisingly easy-to-mod anyway. It's as easy as creating a new "dropzone" folder in the game's root directory and placing your modded files (especially those from this site) in there.
Surprisingly Improved Sequel: Just Cause 1 had some nice ideas, but it was overall a clumsily-made, somewhat awkward game, and was actually that development studio's first effort. They have obviously been brushing up since then, because while Just Cause 1 could have been easily forgotten, Just Cause 2 is awesome.
That One Sidequest: Collecting black boxes for the Reapers. Unlike the Ular Boys' skulls and the Roaches' drug drops, all of the black boxes are underwater. Most of them aren't too bad, but several of them are out very far at sea, requiring you to get a boat or air vehicle to simply get out there, and then you need to swim down all the way to the ocean floor without the benefit of your grappling hook. It's slow and incredibly tedious.
"Black Gold" seems simple enough. Take a Reaper jet and blow up an oil rig. The problem is that the jet you're given has paper doll endurance and controls horribly, and there are a surprisingly high amount of enemies present. This is further compounded in the PC version, where if you die during the mission, the damage you cause to the oil rig does not reset, which could very well make the mission Unwinnable.
The side mission "Stranded" could be made into an entire game all on its own. A pilot gets mysteriously downed on an isolated island that no one visits, is always stormy, and is rumored to be haunted by demons or the ghosts of dead cannibals. You are sent to pick him up, but get blown out of the sky by something. The island is actually inhabited by ancient Japanese soldiers from World War II who think the war is still going on, and are defending their territory with an EMP superweapon. You have to disable the EMP and escape the island. So much could have been done with this.
The factions that you help throughout the game never really do end up taking control of the Island of Panau. The most that ever comes of any of it is that you can recruit them to help you defeat Baby Panak Panay and his forces in the final mission. The ending firmly states that America is going to install a U.S Friendly President, and no option is given for any of the factions you busted your ass helping throughout the game to be that leader.
Given the factions consist of racist bigots, hypocritical assholes, and cutthroat mafiosos, it's probably for the better that none of them take control.