I have thousands of Contacts. I found search results were incomplete compared to native app.
This could be an iOS big though, Contaqs.app search results were better but still incomplete.
UI could be prettier, but app is responsive. I wish iOS provided long-hold help on icons, but this is not an Interact problem.
Group management and the automated contact as are both promising.
Worth exploring but not worth more than $5 just yet. Also compare Contaqs.app.
jfaughnan about Interact Contacts