Thanks for the feedback! Responses below.

> iPhone 4 low-res picture issue

Hmmm, I hadn't thought of how it would impact the new retina display. It looks decent on my 3GS, but I guess I'll have to find a friend with an iPhone 4 to see how it looks on that and find ways to make it look better.

> The two buttons at the bottom seem out of place

I agree with this, and I'm not sure how to best maintain the look of the app, while still having navigation icons that people are accustomed to. I'm looking into this.

> History of transactions, IOUs, email to contacts

Great ideas. I'll add them to future versions.