This is quite interesting. I'm actually in a relationship with an ISTJ right now, for about 3 mths. Although quite short, it seriously feels a lot longer than the actual time spent together. We get along extremely well, have multitudes of things in common and similar interests, and I don't think we ever really argue (except a couple small things). I think she's really caring and she takes mental notes of the things I like and don't like, puts thoughts into gifts, etc. She's also very mature and stands to her beliefs, which I like, and willing to do outdoor things with me.
But some things I noticed are that she isn't very adventurous, in fact, she has a very traditional mindset which I'm not so used to.. since I'm someone that is very spontaneous and likes to try new things, a bit of a risktaker, I suppose...a daredevil, if you will. She's not into stepping out of the box and sticks to what's most familiar.
Another thing is that she's a very tidy person (a bit anal?) and I... well, I guess I'm not so tidy,perhaps.

roud: heh.
She follows all the rules of the system while I follow my own beliefs as long as they seem to make sense.
She's also a hothead sometimes (especially on the road) while I'm the "easygoing" and laidback and patient one...hmm
Still I also haven't heard so much about ISTP/ISTJ relationships and would like to know more about people's dealings and experiences with them. So far it seems to go alright.. but personally I think things would be better if she was more willing to do more adventurous/active things with me at least. For me, that is just one of the main issues. It's nice when people step out from the norm.:tongue: