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.
Awesome Music: The entire soundtrack is quite good, but special mention goes to the title screen music, and Stage 5's music. Considering the composers are the same pair who did Iji's soundtrack, this is not surprising.
Broken Base / Base Breaker: Opinions on the Steam release of A.R.E.S. Extinction Agenda EX from fans are divided. There are those that don't mind the changes in EX while many others loathe it. The fact that EX is being sold as a seperate game instead of a patch doesn't help.
Goddamned Bats: The Sentry Pods, oh, God. They fire three shots simultaneously, each shot going in a different direction. This can be very annoying when trying to rack up combos... Or even trying to get somewhere, as shown by those two vertical shafts in Stage 4.
That One Boss: Stages 3, 4 and 5's bosses are all quite hard, but increasingly so. The worst part? To get SS rank for each stage, you need to kill them without taking damage. Trying to get that Genesis Suit is not easy.
Stage 3 has the Sentinel, which warps around quite a lot, and it has attacks that literally require you to use the ground dash's invincibility to avoid taking damage.
Stage 4 has the Prime Guardian. Its first stage has attacks that are difficult to dodge even when you can see them coming, and then it Turns Red...
The Minos Cannon. There is no achievement for perfecting it, and you can get SS rank without doing so. There is a good reason for this. It is basically Bullet Hell. Good luck with this one.
They Changed It, Now It Sucks: Fans of the original were upset with changes made in EX, such as the simplified mechanics, the redesigns of the female characters (Valkyl was given a more Westernized artstyle, whereas Dr. Carson's design made her look less of a scientist and more of an outright Action Girl), and the levels were made easier than the original game.