I arrived home last night to find an early Christmas present waiting for me, a much anticipated TenX card which I have been waiting around 5 months for. I had already loaded my wallet up when purchasing the card originally so, following a brief activation process through the app, I was all set to go and spend my cryptocurrency anywhere I wanted. I headed over to the nearest convenience store and - to my shock - it worked. The cost of my goods - £46.16. The amount of BTC deducted from my account according to the CoinMarketCap price at the time? £46.18. Allowing some leeway for exchanges providing different prices and the likelihood of the BTC price changing second to second, that is probably as good as you can hope for.
Most importantly, it is far cheaper and easier than using exchanges to withdraw and paying the associated SEPA or banking fees. This is probably the closest anything in crypto has ever been to 'it just works'. I was expecting something to go wrong, or to be charged a huge transaction fee - but no.
The TenX card and app are unfinished at this point, with the card not contactless (ruling it out for day to day use), missing any TenX branding and not supporting other cryptocurrencies (all of which will be added in 2018). I don't envisage it becoming my day to day card of choice even when contactless is added, but it makes for a fantastic alternative to withdrawing off exchanges and is highly recommended.
It also raises the question of just how governments are going to a) assess these for taxes and b) prevent them from stopping tax evasion. You have to fill in KYC documents for upgraded spend limits with TenX - perhaps governments will demand full spend records for everyone registered. This seems draconian, but otherwise it is an essentially untraceable means of spending. The UK allows for up to £11.3k of tax free gains on all profits anyway (£22.6k if married), and so this won't be as much of a concern here for most people, but for those in countries where cryptocurrencies are taxed differently it will be a tempting proposition.
Update 06/01/2018: The TenX card provider, WaveCrest, has now suspended all crypto related prepaid cards. The future is back on hold.