My phone kept crashing

I downloaded this app, and I was super excited to use it because I heard a lot of good things about it, but as soon as I opened it, it was soooo slow and glitchy and whenever I tried to make a movie, it crashed and wouldnt let me open it again. I had to restart my phone several times to even open the app.

Nick Nàme about iMovie, v2.2.3