Essential Tool
It presents a breadth of verbs and conjugations in a clear and readable way. And if this were all it did, that alone would make it worth the price, but it also provides exercises and lessons to help reinforce the reference information it offers.
Although its user interface is intuitive and easy to navigate on its own, the tutorial is a great addition to the app.
I suggest only that a glossary of verb grammar terms (accompanied by a few examples) would be a great addition for a future version.
For example, not everyone will understand the meaning of terms such as “pluscuamperfecto” or “future compuesto” or subjuntivo imperfecto -ra versus subjuntivo imperfecto -se.
Of course, we can always consult references sources on the web, but it would be helpful to integrate directly in the app at least the terms the app itself uses, along with one or two examples of how each verb tense functions in a sentence.
I wholeheartedly recommend VerbForms to any serious student of language who wants to broaden their vocabulary and fluency with verbs in particular. Excellent work.