I got a S2 Apple Watch (the 38mm one) a couple of months ago, which replaced a Vivoactive (pre-HR). I think the S3 without LTE is much the same as the S2.
Battery life definitely isn’t as good for day-to-day but it’s convenient to charge every night so I do – could not bother for an overnight trip but any longer and you’ll be packing a cable. Not that much different for GPS tracking though, a long ride will eat most of the battery of both (although I usually rely on a Garmin Edge for long rides anyway).
I really like all the other stuff – notification stuff is way better, more useful watch faces, daily activity tracking and it’s a much nicer thing to have on my wrist and look at than the flat square Vivoactive.
Oh, and if you do use Apple’s own activity recording stuff (for runs, cycles, etc) now with iOS11 other apps have access to data including the GPS track. So there’s a few good apps like RunGap that can take that and push to Strava / MapMyRun / Garmin / etc if you also have too many places to put things like that.