Patrick Rhone, among other nice people on the Internet, agrees with me that Mingle is a decent return to contacts on iOS:
Mingle is an interesting new action-driven take on a contact app for iPhone. It makes searching for contacts lightning fast and the ability to take action a simple swipe and release gesture. It is one of those things that even the video on the website could not portray well enough. You have to use it to really “get it”. That said, as soon as I did, it became my new go-to contacts app on my iPhone.
The app is good, no doubt, bult like I previously said, the app’s one weakness is its dependence on iOS’s own Contacts list. It makes sense on the one hand, but from my perspective as a user, I feel that it is a hinderence.
Each time I want to edit the contacts I have to return to the Contacts app. Before I used Mingle, I had Siri look up most contacts for me and I was very happy to avoid the Contacts app so I wouldn't be tempted to make needless edits.