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: Destroy All Humans
Anticlimax Boss: An irritating number of examples, though some are more because of you can become rather overpowered over the course of the game (Meteor Gun, anyone?)
Silhouette and possibly General Armquist, though Armquist was definitely more of a challenge. Played horribly straight in DAH!3, in which some of the bosses barely even move, and especially if you have an upgraded Ion Detonator, except for Henri Crousteau.* Breather Level
Cargo Ship: One of the "Ruin Lives" missions in the second game involving a Takoshima businessman's beloved "New Car-san".
Goddamned Bats: Missile launchers in the first and second game. In the first game, they launch a single missile that is near impossible to dodge and does a crap ton of damage to your saucer. The damage is toned down in the second game, and the tracking less potent, but now they launch THREE missiles at once. Add to the fact that on high alert levels, they show up everywhere and can now move, and you will be swooping, ducking, weaving and dodging to avoid the buggers, as they will fill the sky VERY Quickly. And to top it all off, there is a graphical bug on the PS2 version of the second game, which removes the exhaust contrail on occasion, meaning you won't see the rockets until it's too late.
It's Easy, so It Sucks: Destroy All Humans! 2 and 3 are on the easy side. Critics didn't enjoy it. (the third in particular)
It's Short, so It Sucks : All of the games are relatively short. The first two would have been even better if they were longer.
Romantic Plot Tumor: Natalya and Crypto. Natalya even gets some status as The Scrappy, despite the fact that Crypto is the one hitting on her. As mentioned above under Pretend Prejudice, by the time DAH!2 rolls around, Crypto's only concern is having sex with anything female. This is worsed by Natalya, as Crypto falls madly in love with her. And so, as a result, Crypto spends the entirety of DAH!2 trying to have sex with Natalya, not even caring about what his enemies are up to.
Sequelitis: Big Willie Unleashed and Path of the Furon were held in ill-regard by many critics.
They Changed It, Now It Sucks: Many people claim that the changes in Big Willy Unleashed and Path of the Furon made them suck, and that they weren't neary as good as the first two. This is also mostly blamed on the two developers who picked up the series after Pandemic was bought out by EA.