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.
Ear Worm: "He is a, GEX! T-Rex? Uh uh, he's Gex! WHAT!? GEX! He's a wise-crackin' cousin of the tar-pit gang!"
"He's a cold-blooded brother of the B.C. boys!"
Fanon: Gex's last name is Gecko. "The name is Gecko, Gex Gecko."
Flanderization: In the first two games, Gex was generally a Deadpan Snarker who occasionally performed some vocal impersonations of various movie characters and had an affair with Nikki at the end. In Deep Cover Gecko, he effectively became a saurian version of Austin Powers; his comments and behavior were more lewd, he had more interest with sex than with TV, and a lot of his impersonations were of Austin Powers.
Funny Moments: Gex's one-liners will get a few chuckles out of you.
Hilarious in Hindsight: In the Circuit Central levels of Enter the Gecko, on of Gex's one liners is as follows:
Gex: Boys! TRON didn't work once, it's not gonna work twice!
One of the taunts against Rez in the first game was "What do you mean Darth Vaderis my father?". In the second game, Rez declares himself to be Gex's father.
Most Annoying Sound: One of the reasons the camera is so infamous in Gex: Enter the Gecko is because of the incredibly annoying error sound that plays whenever you can't move the camera. Expect to hear it a LOT when playing the game.
Gex's comments are also seen as annoying by many, though the British voice is generally received much better.
Rez and his respective stages, which both add a dark atmosphere to the usually cartoony game, and the floors and walls of the levels appear to be made out of metal and flesh. The idea of Rez abducting innocent people to be mascots for his network is unnerving, too.
The life-loss fanfare from Enter The Gecko might make you jump the first time you hear it, but the game over music is an Up to Eleven horror remix, to really let you know you messed up. Deep Cover Gecko shares a fanfare for losing a life and getting a game over, but fortunately it's more comical than scary.
The mystery level in Deep Cover Gecko. Particularly the part where the taxidermy bear statues come to life and prowl around the mansion.
Porting Disaster: The developers of Gex: Enter the Gecko were unfamiliar with the N64's hardware and it shows. The sequel fared somewhat better, but it still didn't quite match the original.
Also, the Playstation version for inexplicably lacking a save feature.