I've had an Active 20 with full 1:25K UK maps since Oct 2017. I debated for a long time as to whether I could justify getting one, but I needn't have worried. It's been a huge success and I can't imagine doing without it.
A couple of things... I bought a Kent map card to begin with. Then I started buying cards when we went on holidays to other areas. It occurred to me that a full UK card would save money in the long run so I bought one. The downside is that the full card doesn't have 1:10k street maps, which I sometimes found useful with the 'local' cards. Also, (and I can't remember exactly why) putting my routes on local cards was more convenient than putting them on the Satmap's internal memory, but although I can put them on the full UK card, my routes aren't accessible from there - even though there's sufficient space for them. I'd be interested to know if you get that issue.
Finally: although access to Satmap's Xpedition2 mapping system was included, I didn't like it at all and I use OS Maps to plot routes and copy them to the Active 20.
First impressions in use yesterday were excellent - highly accurate and visibility of screen very good. My full card does have the street maps, so perhaps they have changed the spec. It's chunky, so I am working on where to carry it so that it is accessible - I have got a belt clip for it and a lanyard.
I also got a subscription to Xpedition2 - and I have an OS subscription. I think the Xpedition software has been worked on, though I am not yet convinced by it. For example, I cannot find an Aerial view on Xpedition, which I find useful on the OS app for paths not shown on the map etc.
Not sure about the accessibility of routes on the card - I saved yesterday's on the internal memory - I will report back when I have used the card memory.
First impression is that it is a step up from my old Garmin 64 - time will tell, though.