They are very well done, actually; and the English dialogue versions (the ones I've so far encountered, anyway) are among the best I have yet encountered in the genre.
There are hardly any language or verbal style 'clashes' when someone didn't get it quite right. I have found that happened quite a lot in years gone by, but it seems to be almost entirely eliminated here, and it's very colloquial.
Of course, my (by now an open secret) preference for cuteness leads me to having developed a soft spot for the shy Mikuru Asahina (the other possible candidate, Yuki Nagato, turns out to be an android, unfortunately), and who even has her own fan club, I notice – but that's just me, and getting to be so predictable of me, I suspect...
Anyway, it's an interesting set of stories, involving time travel, reality warping, androids, aliens and espers, among other ingredients, and yet quite easy to digest and not too difficult to follow all the twists and turns. Recommend for sheer enjoyment and for being very engrossing!