Things work pretty well for me and my ESTP
I will say that earlier in our relationship we did have to work out the extracurricular flirting bit. It's not as bad as it sounds though, so long as the ESTP is actually interested in settling down; I wouldn't recommend trying to reform one who wants to play the field. The issue we had was that he (like most ESTPs) is very outgoing and playful, and stuff I considered flirting he considered just being himself. He was willing to set parameters to keep me happy though. And definitely putting your foot down works wonders with an ESTP. They naturally enjoy testing boundaries but if you are firm they'll respect you.
On the positive side, I feel like INFJs and ESTPs have tons of chemistry. Even after 6 years of dating we're very affectionate and have lots of snuggle time. He admires my intelligence and compassion and I admire his confidence and ability to let loose and live life to the fullest. As an INFJ I tend to be rather regimented and overly-serious when left to my own devices, but he keeps me laughing constantly and having fun.
I actually don't think I could handle an ENTP in a relationship. I love having lively discussions with my fiance's ENTP friends and they are some of the most hilarious, zany, and fun people I know, but to me they seem a little like ESTPs on crack, and I mean that in the best possible way and as someone who really enjoys and admires the company of ENTPs! ESTPs like to push the limits, but eventually they'll settle down and respect the constraints of a given situation. ENTPs don't just toe the line, they stomp on it and then keep going. Also, many that I've known seem to have some trouble with monogamy, such as our friend who dates an ISFJ. My apologies if I'm offending any ENTPs out there, I'm sure many are more mature and responsible than my fiance's friends so I shouldn't generalize. Also female ENTPs seem to be a different breed altogether; I know one and she is very low-key, I actually mistook her for an ESTP until she took the test with me.