Having applied for access to the new Proton Bitcoin Wallet they emailed me today saying I now have access. So here's my experience so far- It opens easily and has a 12 word seed. I tried using that seed to create an Electrum wallet but Electrum did not recognise the seed phrase- so not sure why that was. Proton claims their wallet can be used to open any wallet using the same BIP39 mnemonic and 12 or 24 seed words...so not sure why Electrum could not create a wallet using Protons 12 word seed phrase? The Proton wallet links the user to buy Bitcoin via two secondary merchants so I decided to try the one that offered the best price- Banxa. You move from the proton website to the Banxa website for this. I entered the name address and ID they requested an then paid via a credit card and payment was accepted. The link showed payment confirmed and ID approved but then about an hour later an email was sent from Banxa saying the transaction was cancelled and they would refund my credit card. No explanation why. Have not tested the wallet for transactions as there is nothing in it but it seems ok so far with a fairly intuitive layout but the service from Banxa was of a below average standard IMO.