Another idea: Since Apple knows exactly how much money I've spent in their store, that signal can somehow also be weighed in with my reviews.
This means that reviews by people that have spent a fair amount in the app store would get a better/heavier scores than those that have not yet spent as much money in the store.
Use feature detection rather than browser/UA sniffing. Tools such as http://www.modernizr.com and http://www.headjs.com (limited feature detection but also provides other features) can be very helpful.
Thanks for making it free. I'm trying it out right now. For me, it lacks one critical feature that another competig app seems to provide: a timer. I'm using both discrete counters and timers to time tasks and completion time. Not a big issue, but something to keep in mind. Thanks for making it free and all the best!