Argyle King
Legend
I can see changelings in particular leading to bad experiences in play.
I find warforged and shifters very evocative and have great potential and players have played reskinned versions of them in my homebrew campaign to great effect. Changelings and the psionic people are aspects of Eberron I find less fun.
The very short version of what I talked about in past threads is essentially this:
Every step of the way, any possible NPC -even the one that hired the party to track down the villain- could turn out to have secretly been the villain, and that's how the villain always remained one step ahead. Even when the party did manage to defeat the villain... well, surprise... he's still alive because that was actually a different Changeling that he hired to make you think it was them, but it wasn't actually them, so he's still alive.
That experience caused me to question the entire premise of the setting. How does a setting with the potential for political intrigue and grayer morality function when a common element of the setting is never being able to be sure that the person you are talking to is actually the person that you're talking to?
Since then, I've also had the misfortune of being in (non-Eberron) games with players who are Changeling PCs who have some weird fetish of tricking NPCs into sleeping with their character.
In general, the implementation of the race/species isn't something I like. As that race/species is a core part of Eberron and I still have the unfun experience in my mind, I don't enjoy the setting -which sucks because there are a lot of parts of the setting that I think are cool ideas.