Hi.
I'm considering purchasing Gex, as the game seems appealing to me with it's style and setting as well as being a piece of well-aged classic. However, having relatively recently completed the first Oddworld game, one thing bugs me - is Gex frustratingly difficult (the feeling I got about Oddworld), or just "regular" to play? At the moment, I don't feel like attempting anything hard as hell ;)

That's for sure :) Like I said, I'd consider Oddworld utterly hard.
What you say is not in favour of Gex for now, so I'll skip it for the time being. Perhaps gotta wait until a sale, then it will be worth it.

Yeah, I'm not trying to diss Gex, but to say it would be a romp in the park would be an outright lie. The only favorable thing it has going is extensible hit points and power ups.

This game is brutally hard. It seems to actively try to hinder your progress. Worth playing if you are a 2D platforming maniac or have nostalgia, but otherwise there are better games out there.