Poor documentation, hard to extend, breaks other forms

This review is for version 3

pros:
– nice interface to create forms
cons:
– hard to extend with custom functionality
– poor and badly organized developer documentation
– breaks other forms on the same page, e.g. woocommerce forms (had a ninjaforms newsletter signup in the footer on every page)
– poor support (at least with free version)

conclusion:
– may work nicely for most standard cases, but if you want to customize you have to dig deep