Personally I want more information than just distances to the green. I want to know how far to carry that hazard, or how far can I hit and still stay short of that bunker? How far is it to far side of the fairway in that dogleg? I use my Garmin G5 to answer those questions and more, just as often as I do for distances to the green. In fact I find it more useful for that because I can get green distances from course markings on most courses if I need them, but I can rarely get distances to other features. The watches may be less expensive, but the minimal information they give is a total waste.
I had one of the original GolfLogix and it was only marginally more useful than the watch. It wasn't until I got my Approach G5 that discovered just how useful a GPS can be. Like the S1 watch it has no fees attached. All courses are preloaded, and updates are free.
One potential downside to the smart phone apps... there is some question about their legality under the rules, depending on the apps you have loaded. Using them in competition is a bit of a grey area right now.