Well, that's not a fair question. Lots of people need to have others create the words and images that they send to their friends and loved ones. The rest of us have our own ideas. We know what we want to say and how, or we find images of artworks that deliver some message uniquely well. This is for the rest of us.
This form produces one card from each 8.5x11 sheet - folded, that's a bit bigger than a 5x8 file card, somewhat larger than most greeting cards. The cards take inkjet printing beautifully, they're lightly scored for precise folding, and, even with the costs of ink and whatnot, come out far cheaper than any store-bought card around. The Avery web site offers templates for aligning your art to the forms, clip art, and other free aids in using these cards. The templates take the guesswork out of laying out the card; I haven't tried the other tools they offer.
I have only one minor complaint, that the envelopes aren't the most opaque - no big deal unless you have a sensitive message or want opening the envelope to reveal its surprise.
That problem isn't big enough to stop me from using these cards or stop me from coming back for more. They aren't the fanciest around, but perfectly fine for most kinds of notes and greetings. And, most importantly, these cards carry my own thoughts, not some Hallmark writer's.