Only effects 9mm pistols.
No problems, other than the cost of feeding them enough. They are very hungry...
Wife's Gen 4 G26 has about 500 rounds through it and not one misfeed. Even with extended 17 round mag. It did however get polished and trigger job from 8 to 3.5 before we ever shot it.
I wouldn't let it scare you even if you got a 9mm. They are easily fixed for cheap or glock will fix them for free. These problems happening are rare, it's just that so many glocks are made/sold that the seem to appear frequently on forums.
Ejection issues, lots of them.
Glock will fix it if you get one with a problem though