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: Victoria: An Empire Under the Sun
Ending Fatigue: Many players rarely make it to 1936, usually ending their games around 1910 or so. Part of this is that the game mechanics, though great for simulating the first 80 or so years of the game, start becoming less believable once the 1920s and 1930s roll around.
The game also begins to suffer serious slowdown on most PC's to thnks to the absurd numbers of pops it has to keep track of which doesn't help.
Game Breaker: While the two principal German nations Prussia and Austria are by themselves no means weak when either one of them meets the right conditions they can form Germany and if one controls all German territory then they can form Greater Germany. The bonuses and advantages of Greater Germany are so numerous that they can basically overwhelm and easily beat even the other great powers of the game.
Westernized China has Memetic Mutation status as Game Breaker. 1/5 of whole population at the game start is under China's control and in final years of game it's still about 1/6. Good resource base. Mostly pathetically weak neighbours. We Have Reserves after the military starts to use modern equipment turns every single war into series of Curb-Stomp Battles, where Chinese will simply overwhelm their enemies with absurdly large armies without much effort. If everything goes smooth, China can westernise as fast as late 1860's (the game starts in 1836), giving you plenty time to heavily industrialise, research the most vital technologies and easily participate in Scramble for Africa, which can turn into painting it whole in yellow. As of new version, it's still possible to modernize quite fast through conquering, but receiving the best of all the techs that have been researched when Westernizing no longer happens.
Stop Helping Me!: The sequel sees Belgium start the game in the United Kingdom's sphere of influence. This would be a great military advantage if there wasn't a world iron shortage coming on, and the UK didn't have first pick of its sphere-members' iron.
Of course, if the UK WASN'T helping Belgium, it would be called "Southern Netherlands."