Generally, the question is not if AirDrop is safe or not – but what the file being AirDropped is. AirDrop is just a file-transfer protocol and does not guard against malicious files.
iOS is pretty safe when it comes to this kind of attacks, but no operating system is bullet-proof. If you want to stay on the safe side, do not accept any kind of file transfer (from any source) from strangers just to satisfy your curiosity.