Hey! Ok so I can kind of give some thoughts on this combo... or at least close to it. I'm in a relationship (and LOVING it) with an ISFJ. Granted, the N/S is a big difference, but I'll comment on what I know. I find that being a male E in a relationship with an I is great. It makes things more balanced and not too quiet while not being overly talkative either. Having the F in common is what is most important to me, I believe, because we think so similarly it's eerie at times. The J is also a godsend, because I am borderline if not in denial OCD and she is VERY J as well. All in all, that works out great!
Now I know you didn't specify so I won't assume the relationship in question is one involving you, but I find that after the N/S difference in people is the one that least bothers me. Sure, if someone is REALLYYYY P, I hate it. I can't stand disorganization. Also, I find a stark difference in the T/F line between myself and others to be secondly most annoying. I don't mean to say that I find any type to be so irksome that I can't put up with them, but in relationships I find that the more similarities, the better, typologically at least.
Finally, one last word on this. I am in contact with a great deal of type conscious people, all of whom are absolutely brilliant imo and I could never hope to rival their knowledge, but recently this sort of compatibility question came up over coffee. They came up with the theory that the best relationships are those that share the dominant function. That's something to consider

If this IS about you, then best of luck! Hope I helped in some way
