We typically order our holiday cards via Shutterfly and have had great experiences with them.
With an amazing variety of designs for every type of holiday card ( happy holidays / merry Christmas / happy new year etc etc), each with a great range of prices ranging from $$ to $$$ you simply cannot go wrong.
Over the years I've learnt to collect coupons for free custom envelopes ( no need to purchase separate address labels, yay!!) and stack on the 40-50% off and free shipping coupons to maximize savings.
I've always received several email notifications about the status of my order and shipment usually happens within one business day!
I can't say I'm a huge fan of the app though as it's hard to make edits and customize your projects unless you are working off a big tablet. And the app doesn't allow you to even "view" past/saved projects ... it requires you to open it separately in the browser which quite defeats the purpose of having the app.