I am considering selling my SS S2 Milanese Loop AW to replace it with S4 black aluminum. While I love the look of the silver stainless steel, and how it can to be paired with basically any possible wrist band / color, I am over with swapping bands etc and just want something more cost effective and simple. Like others have said, loosing upwards of $500 on a watch in a year is no fun, and forcing myself into waiting for a next gen because of the depreciation, kind of takes it away from the overall experience (at least for me).
The problem with Apple Watches is that Apple is at baby steps stage, compared to where they are with iPhones, so this means that that there will be always significant improvement to the CPU and overall performance of the watch which would make the upgrade very tempting, unlike the iPhone, which is already a CPU/performance beast and yearly upgrades leave a lot to be desired. 3-4 years old iPhone performance (user interface etc) about as good as brand new iPhone, a year old Apple Watch, performance like crap compared to the latest Apple Watch - I think this trend will continue for several years for Watches.