Looks like a good way to fill their marketcap expectations.
This is a great first step. And I'll have to go look at my energy bill... but I think it's super important to keep scale in mind. The 10 kWh unit may do the trick for your house, and could certainly help in the evening offset if you have solar - but for backup? and if you drive an electric car? Plan on buying several. My little Leaf has a 24kWh battery. The least expensive Tesla Model S has a 40 kWh battery. So if you need to be able to charge your car AND run your house in an off grid situation - you'll need several units. Luckily - the price is reasonable. This is super exciting. I loved the diagram showing the US and the little blue square showing the amount of solar panel real estate needed to power the country.
It's true that you'd need several units if you want to fully rely on the powerwalls to power your whole house, electric cars, etc. I also read somewhere that its price isn't currently economical. However we must remember this is a first generation tech. Like all new tech will take several iterations before it's perfect but as you say it's a great first step. Plus it'll hopefully kick start a new industry of home energy storage. Also competition in this area should speed up the R&D of batteries in general which will benefit all electronics, including electric cars range. I bet you wouldn't say no to a battery pack upgrade to your leaf ; )
It sounds reasonable now, compared to what expectation was. But I hope you're right, nonetheless. mk and I were just discussing how we hope this spells the end of gas or diesel generators. As it stands, I'm pretty jealous of people who have solar panels. My roof configuration is too optimal to install them. My next house, though, when I have the money to build it from scratch, is definitely going to be as energy independent as I can afford it to be.