Dwolla is one of the many ways you can transfer money from your bank into Mt. Gox to purchase Bitcoins. It takes the longest but is also the most above the board method. If they can make it easier to do this they will surely gain an advantage over the shady (looking) russian sites offering the same things.
Dwolla better than Bitcoin? Way, way better marketed. Better UX.
Dwolla can improve its tech stack and have it be the UX layer on top of Bitcoin if it chooses. I guarantee you there are folks at Dwolla working on this. Dwolla = front end of payment protocol. Dwolla = bank?
Competing payment protocols = Bitcoin; Bank routing/Swift + Forex. There were efforts to abstract gold into a payment protocol in the 90s but they failed.
Bitcoin or one of its numerous derivatives (feathercoin, litecoin, terracoin, ppcoin, ixcoin, novacoin, namecoin, freicoin, "govcoin") will likley win as a payment protocol.
The bitcoin investors have zero incentive to spend the money marketing it and building a sexy interface on top of it. There is money in interface.
BTW, a paypal competitor IS interesting! It's a 10bn+ market. but dwolla could be the "bank". it could be the secured storage. ....
note: andreesen has also invested in ripple/opencoin. reminds me of their simultaneous bets on dalton cadwell (immeem)'s picplz, and instagram.
Andreessen Horowitz just put a lot of money into OpenCoin/Ripple, I guarantee you they are going to knit the two services together. Dwolla w/ happy PR buzz, back end provided by OpenCoin.
Maybe I'm missing a killer feature, but Dwolla doesn't seem all that interesting, just another paypal competitor.