The Quickbooks support is the killer app here.  The articles almost bury the lead.

Along with Quickbooks integration you get the whole basket of compliance regimes that every small business needs in order to feel very confidant that they are going to be able to use Bitcoin just like all their other payment methods without any new headaches.

They get GAAP, they get clear unit of account, they get tax compliance, they get a way for their accounting to accommodate it without doing any extra technical stuff.
The merchants want to focus on the things that make their business a success.  Keeping their inventory fresh, providing great service, being awesome at what they do whatever that is.  This provides them the opportunity to do that rather than deal with the arcane ephemera of Bitcoin issues.

Well done BitPay!  Adding Quickbooks is going to make getting the next 10,000 a LOT easier than the first 10K.
I've been asking for this for quite a while and am delighted by it.

This is not a huge development, but the impact is GIANT.  Now with BitPay+Quickbooks, Bitcoin can accelerate and reach mainstream marketplace adoption among merchants.

There are going to be a lot more places to spend your coins.