I'd be concerned about safety and removal of them... I mean how many decades do you expect to live for? They've not been tested over that time period.
problem is that someone's going to need to be the first to "test" something like that over the time period
given things like pacemakers, replacement valves, stints etc are common enough practice in medicine i'd say we're good enough at making something to survive the conditions of the human body for a long time.
Also would be better to have a more universal one than something linked to a particular company - it might be useful to have one that will unlock the door to your house, let you purchase your lunch, drinks in a bar, use the tube/train/bus etc... that is more the sort of thing I'd consider.
At the moment you can fit one yourself and have it unlock your house front door... but for a company like this you'd need a second one fitted by them if volunteering for this and then what happens when you change employers and/or some payment solution comes out in the form of an implantable chip etc..
it would be handy to have something more universal, but it doesn't need an implant, it'd be handy to roll your passport, drivers licence, national insurance, eu health, bank and credit cards all into one single item.
of course it'd need to be an option rather than a necessity, forcing it on people isn't ideal.