Considering how expensive some jeans are today, I would put them on par with most suit pants. 🙂
Seriously, I try not to judge people by what they are wearing, but sometimes you can’t help it, because what they wear is not appropriate to the time or place, and one hopesd and expects that a frum person will show seichel and sensitivity. Jeans are great on a picnic (just as I believe it is inappropriate to wear suit pants on such an occasion), but they don’t belong on Shabbos at Shul or at a simcha, unless it’s at a BBQ. I don’t think that people who wear jeans, though, are not frum. Neither is every guy who wears suit pants frum, either.