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.
Base Breaker: There is a split on opinions on Billy the Kid. One half of the fanbase are willing to say that he was well-acted and functioned well within the team and for the most part is respected for not being as obnoxious and cliche as he could have been and for facing death like a hero. The other half... well... just see What The Hell Casting Agency below.
The reaction to a possible "female Expendables." Moving on...
Complete Monster: Rogue CIA agent James Munroe, The Big Bad of the first film. A drug smuggler and mercenary, Munroe is responsible for his partner, General Garza transforming the island of Vilena into a Police State, using the people as labour in their drug operation. During his first scene, Munroe kills one prisoner, then derides Garza for his lack of spine, forcing the General to murder a second prisoner in order to save face. When the Expendables raid Vilena, Munroe captures Garza's daughter, Sandra, who opposes her father's government, and has her waterboarded over Garza's objections. He contracts former Expendable, Gunnar, to kill the rest of the team, and when Garza turns on him following the Expendables' assault on Vilena, he shoots the General in the back, kills the rest of his security detail, and tries to make good his escape, though not before instructing Paine and The Brit to torture Barney Ross, and taking Sandra hostage to use as a Human Shield. Caring only for his profits, Munroe is willing to wreck an entire country in order to increase them.
Also the close-up of Ross stabbing one of the mooks who were going to rape Sandra. Doubles as Special Effects Failure as the blood looks rather off in the shot and his knife kinda wobbles around unnaturally.
One-Scene Wonder: Trench and Church, played by Arnold Schwarzenegger and Bruce Willis. The sequel gives them more screentime and action sequences. Also, Mickey Rourke, who has about 5 minutes of screen time yet gives arguably the best performance of the first film.
Reality Subtext: Possible case in that Barney's speech following Billy's death could also apply to the death of Stallone's son in Real Life:
Barney Ross: Why is it the ones who deserve to live, that want to live the most, die - and the ones that don't deserve to live, keep on going?
So Cool It's Awesome: Both movies. Considering the fact that both movies are the revival of the action movie genre, this is to be expected.
Took The Bad Film Seriously: Many critics who didn't like the movie were nevertheless impressed by Mickey Rourke's performance and wondered what such a dedicated performance was doing in a "brain-dead action flick". Oddly enough, a lot of critics, in an odd version of this trope, were expecting slam-bang action all the way through, but complained about the overuse of CGI (which was not a staple in 80s movies), the too-modern Shaky Cam, and, most unexpectedly, it having too much plot.
What The Hell Casting Agency: While the fandom seems to be rather accepting of a female presence on the team, the more vocal reaction to Liam Hemsworth being cast is vehement to say the least. Reasons vary; from him being too young, to not having an action movie to his credit, note The Hunger Games was being made at the same time as The Expendables 2, both films being produced by Lionsgate, so he was probably cast to cash in on the films success, which, in the eyes of some, doesn't help his case much. to his relationship with Miley Cyrus. Don't ask.
Though people stopped complaining once that found out that his character dies not even 20 minutes into the film