Local Storage is a neat concept but since it is a String:String key:value pair store you’ll need to deal with conversions when dealing with numbers, dates, maps, arrays, etc.
The 5MB Safari limit also makes large scale apps just simply not an option. However the simplicity of the API is appreciated and thus Mozilla’s localForage framework http://mozilla.github.io/localForage/ is a great alternative with a very similar (but async) API that sits on top of the more capable IndexedDB APIs.
Hopefully in time all browsers will support the Quota API and or increase the localStorage to a realistic level! 