I actually agree. I've owned MANY battery cases, for many models of iPhone, and I'm excited to receive my Apple battery case. A soft case like the silicone apple case I've had on my iPhone 6 for over a year.
Most cases are rigid, tough plastic that typically snaps together in two or more pieces. Bright LED lights that you can't disable while it's charging, and on/off switches that I've never understood the point of. This case fixes all of these issues, and is only thick where it has to be. It's not thick at the top and bottom where the battery isn't. Yes it's weird looking, but actually looks like it will be comfortable to hold.
The only drawbacks are it's less mAh than most of these cases, and it's expensive. Considering the smart features, partially slim profile, antennas, and lightning port, I'd say those things are easily ignored.
People need to get off their high horse about "design" and "Steven Jobs wouldn't have allowed this". This is a mostly elegant way of providing additional power and doing a decent job of it.