Spent a fair bit of time comparing a Satmap with a Garmin GpsMao64s for walking/running duties (as I wanted proper buttons for use with winter gloves). Went with the garmin in the end, but both pretty amazing bits of kit. Garmin screen seemed a little easier to read in bright sunlight, but main attraction was familiarity as we already have garmin bike (edge) and running (forerunner) devices and know our way around garmin connect.
I’ve used both Garmins – mainly outdoors ones – and the Satmap, both the 10 and the 12 and while the Garmins tend to be good on the hardware side of things, I still find the interface really non-intuitive, though you get used to it. The screen on the Active 12 is great, really clear, and the interface is good too, just very logical and easy to use.
It’s not 100% waterproof in the sense of being submersible for minutes – not ideal for kayaking say – but it is pretty much splash proof and I’ve never had issue with it on the bike. You can buy a fully waterproof cover if you choose. The screen protector scuffs up really easily – it’s a clip-on polycarbonate thing, and water gets under it and dries out leaving scummy deposits, but you can discard it and fit a stick-on protector to the actual LED screen or on top of the polycarbonate clip-on shield.
You also need to use Satmap’s own software to upload and download GPX files, but it’s not a big deal to be honest. Ultimately I suppose I just find the Satmap a nicer experience all round, but plenty of people use Garmins quite happily.