I quite enjoyed 'Learn Spanish - MindSnacks'. Its a fun way to learn numbers, phrases etc. Good for beginners.
For vocabulary, I found one called Spanish Vocab by a company called Brainscape. It is a flash card app with like 4000 words. I have learned a ton from it.
Tried a bunch, but none of them came even close to the Duolingo experience. A duolingo app would be awesome.