Update: Looks like Google let the developer restore 4.4 support to the existing app. So...you can have Facer again.
When it comes to rolling your own watchfaces, few apps do it better than Facer. It's crazy-customizable, feature rich, and easy to use. I figure at this point most hardcore Wear users are sporting it (or have at least tried it out), and today it's getting a pretty significant update. Here's the long and short of it: the app itself is now using Material Design. Yay for that. However, it'll only work with devices running Wear 5.0, which only started rolling out today. Boo (for now at least)! Eventually, all watchfaces will have to support the official APIs in Wear 5.0 or face Google's ax, so it's unsurprising that Facer has already made the move. Still, that's going to leave a lot of users in the dark until 5.0 hits their respective watches.
Aside from those changes, there are new watchfaces along for the ride, and it should also use significantly less battery (that's a big benefit of Wear 5.0). The update is live now in Google Play, so go ahead and pull it if you want...or just wait till your watch is updated to 5.0 so you don't lose Facer functionality in the meantime.