Re: What will it do to the other companies selling digital OS maps?
Been using the OS subscription service for a while (didn't realise it was Beta) but have a number if issues with it as compared to my preferred desktop OS mapping: Mapyx Quo. For example OS app is picky about GPX file formats. It even failed to read back in a GPX file I exported from the app.
BTW if you've looked at the digital maps in the past and balked at the cost, look again, I got all of UK 1:25k and 1:50k for £125 (from Mapyx on special offer). Quo isn't perfect but I've tried several alternatives and it's the most versatile, primary gripes are that some commands/settings are hard to find and there are still a few irritants if using it on Win10.
As my primary use is for off-road map updates are not a big issue. In practise I mostly use Quo for planning then print off the map(s) I need for the hike. An A4 sheet of today's route is a lot easier to handle than an OS sheet and I'm never going to rely solely on electronic navigation devices. (I often enlarge the print image too so I can read the map without my glasses).
Mobile phone battery life is a big issue (worse in the cold) so I use a dedicated GPS (basic, no in-built OS mapping) which has better antenna so captures more satellites faster than mobile. That runs for 18 hours on 2xAA batteries. I don't regard a mobile mapping app as being as good and reliable as hard-copy plus GPS location.
The focus of this article is on the mobile OS mapping app but the license also gives you desktop (web-browser) access and a big screen is an advantage to see overall image of an area/route.
Bottom line is I make little use of the OS app - but it's under 20 quid a year and it's sometimes a useful additional reference.