Here's what you get with bitcoin:
1) Transaction fees on a per transaction basis (boo!)
2) No interest (super boo!)
3) Moderate resource load on your computer (downloading the blockchain requires a paid for internet service - fail), although in the long term the resource load will be insurmountable 3_ (100GB blockchain some day)
4)No insurance and nonexistent client-side security unless you spend money / time / effort properly securing your wallet (super duper boo).
1) The transaction fees amount to less than half a US cent. Online transactions involving banks frequently go through Paypal, which charges something like $.30 + 2.99% -- wires can be quite expensive, and checks are sloooooooow.
2) If you're just holding your government fiat, it's probably declining in value. Just as you take a risk in investing your money in a bank through deposits (though the FDIC point's certainly valid), you can deposit with BTC banks, where fairly reputable members can offer upward of 12%
MPR with "dynamic deposit" in the form of GLBSE assets which can be immediately withdrawn.
3) Grab a thin client like Electrum if it's a problem. The devs have sound plans on how to solve the storage problem when it becomes significantly large (blockchain currently amounts to less than one percent of total storage capacity in the vast majority of HDDs on the market).
4) Encryption already exists in the "official" Satoshi client. With the Armory client, security is taken to a whole new level. As for FDIC insurance, I doubt we'll get the USG to create an agency to handle bank runs, but there might be other options if the market wants it. For now, when lenders are desperate, we resort to inter-lender loans to cover deposits and any other liquidity problems.
