Everything is massively faster, and I get 2.5-3 days on one charge. With my S0, I would run out of juice about an hour before bed. That was the only reason I upgraded, but very glad I did as it's much better to use.
I’ve had my series 0 since July, 2015. I’m due for an upgrade this year I think. My zero doesn’t frustrate me much, but I’d say some things are definitely laggy on watchOS 4. I get tired of having to ask Siri to do something multiple times when it used to take only one time.
So my question is whether the Series 3 GPS is worth paying an extra $130 for over the Series 1? You can find the Series 1 for $200 these days, and I don’t really care about having the additional water resistance or built in gps and altimeter. I suspect the 3 is quite a bit faster, but if the Series 1 is significantly faster than the 0, I’d probably be happy.
Personally, I would not upgrade to Series one. Series One is virtually is the same thing as the first generation Apple Watch, with only an upgraded processor, which is faster if that's all you are considering. But being this far into the release of the Apple Watch series, I would likely consider the Series 3 GPS model only if you can justify the added features. You would have the faster dual core processor, improved battery life, audible Siri (Which is much more functional). Considering the future And given the approach of watchOS 5, the Series 3 Apple Watch would likely be much more suited, being we don't know how Series one will likely react to that version, similarly to the first Gen Watch compared to WatchOS 4.
Game changer. Nothing lags and I can install as many apps as I've wanted whereas with my S0 I ran the bare minimum. My battery also now lasts all day and then some. S0 had to go back on the charger 30 minutes after exercise and even then it barely made it through the day.
The latter is especially important on my wife's 38mm since it has a smaller battery compared to the 42mm watch.