What makes this any different than using Electrum for Android (in airplane mode), or a separate air gapped computer with Electrum?
There is also another hardware wallet called Elipal Titan that is completely offline and uses QR Codes.
1) To my knowledge, you cannot use your own entropy on Electrum. With our wallet, you can generate and use your own entropy very easily.
2) Using an air-gapped mobile phone (Vs. an air-gapped computer) brings you convenience (i.e. you have access to your cold wallet almost anywhere). It is also easier to scan QR codes with an air-gapped mobile phone.
3) Elipal is expensive and has the typical hardware wallet vulnerabilities:
https://en.bitcoin.it/wiki/Hardware_walletWith our wallet, since you choose your own hardware to install our app, you considerably mitigate such vulnerabilities.