There's certainly no shortage of companies offering very similar products and doing well for themselves.
And having the minimum plan @ $5 pm (more than I pay for CrashPlan) it's not at all value for money. Maybe it's fair but my needs are lesser.
We're gonna be putting up our about info really soon but we wanted to get the product out as soon as we could to get some initial users.
The demo video gives a good overview of what app looks and feels like.
You're right there are many bookmarking apps and most of them are really good so we are taking a stab at a problem that's been solved many times before. ;)
Then again, I have a touch of ADD, so I may be your 'worst case scenario'.
I wish you success!
Did you have any problems installing the plugin, or did you just have trouble finding the page that links to it?
I'd also be interested to know what you think your USP is - not sure "we've focused very much on building a solid product that looks and feels native and runs fast" is enough. If anything it should be a given.