Is GBA4ios safe?

Hi! I have an iPod Touch 5. I just found an app called GBA4ios that simulates a Game Boy Advance. I've seen tons of people use it, but just found out it's not offered in the App Store. I was trying to figure out if it's safe or not to download. I've done a lot of research and have found no bad reactions with hacking and viruses or anything like that, but want to see what you guys think. I'm hesitant to download since Apple does not offer it, but have found no reason to find it dangerous. What do you recommend in a situation with downloading things outside of the App Store?