The problem, you might have surmised, is that you're buying what's currently a vendor-exclusive technology. You can't just run to any store and pick up an NM Card when your built-in storage fills up. It's unclear how Huawei will price these cards, for that matter. And however reasonable the price might be, you're likely locking yourself into using Huawei phones if you want to use that extra storage with any future phones.

Our colleague Evan Rodgers put it well: a proprietary card format is one of the reasons Sony's PS Vita never really took off. People aren't as likely to invest in removable storage if it's only ever usable with one company's devices, and there's a strong temptation for companies to charge a premium knowing their customers don't have a choice. Huawei won't necessarily charge an arm and a leg, but it could still end up repeating historical mistakes.