Oh yeah, I totally recommend it. Well, now with Android Wear supporting Watchfaces API, you'll see a lot of custom ones on the Play Store that may have more functionality than Facer (at present, Facer can only access battery status and weather, no Agenda items), but with Facer at least all available options are free. And just as with 'native' faces, the more fancy stuff they have, the more they'll drain your battery.
With 'normal' watchfaces I get the same battery life with the stock Moto360 faces than with Facer. And even with the stock ones, if you use the more animated ones, they do drain your battery faster.
Now that you can disable the wrist action to turn the screen on though, you might be able to save some battery too. In my case, when I was driving the watch would turn itself on with every bump and turn I made. Not anymore!