If you’re looking for a smartphone wallet, then the MyCelium wallet might be a great fit for you. Sending and receiving can be almost instantaneous, making it decent for storing and using small amounts of Bitcoin. The only drawback is the potential security threats of it being online. As with any device that is continually online storing private keys, security is never 100% guaranteed. While you likely won’t have a problem with security, it’s worth noting that the use of a hardware wallet that keeps your funds offline would be a much more secure option.