I haven't interacted with INFJs enough to determine whether we could have a thriving relationship, so take what I say with a grain of salt.
Depends on the particular ENTJ and INFJ. I find many INFJs to be adorable, the kind I'd want to cuddle on a fall afternoon, but there are things that make me step back. I need somebody who gets fiery when they see people mistreating others, and I get the feeling that most INFJs are the type to 'mediate', even when there is a clear victim and aggressor. On things that really matter (and for me that is morality), I believe that there is no wiggle room.
Do I feel like a master? No, but I feel like sometimes (emphasis on "some"), they hear me say a few wise-sounding words, and start putting me on a pedestal. Too rebellious? Pfft, no! Too mysterious? No, but ya'll tend to keep quiet when there are important things to share, especially heavy feelings.
Te vs Fe? That can be an issue. I think this is where my idea of flexibility comes. Te/Fi and Ti/Fe don't get along very well, IMO. The INFJ may wonder why the ENTJ can be extraordinarily unyielding at times, and the ENTJ may wonder why the INFJ is extraordinarily wishy-washy at times. The ENTJ will viciously tear at people's throats, while the INFJ will accommodate too much in exchange for social safety/calmness. Now how does this affect a relationship? I don't know. Perhaps the best result is that they learn from each other and grow into stronger individuals as they grow closer to each other.
EDIT: Here's an interesting look from the Socionics side of things -- ENTJ/ENTj is the "supervisor", while INFJ/INFp is the "supervised". The description accurately portrays my interaction with some INFJs.
http://www.socionics.com/rel/sp.htm
