Edit: Loving the gifs btw!
The balance displayed is much less than what the wallet contains, because of the internal addresses from the key pool.
See http://blog.barthe.ph/2014/04/03/bitcoin-balance-differs/
Seriously, though, this is kinda neat.
If someone uses a new Bitcoin address for each transaction, there is no way outside of statistical analysis (which may not even work in many cases) to know which addresses belongs to which wallets.
I do wish that you had a transaction history more like Mint does. The balance only isn't too useful for me.
Transactions are in progress (https://balances.io/transactions). Definitely something we want for ourselves as well, and we'll get it released ASAP.
If you require plausible deniability to be safe or avoid incarceration, I would recommend not using Balances at this time – I obviously can't guarantee that we are safe from a very motivated intruder, but we have taken many paranoid precautions to avoid such a breach.
It's almost a view into the viability of the market (or whatever it's called) to see how many competitors comment - the more, the better. Right?
Check out the beautiful http://getfortuneapp.com/