Todd Zywicki of George Mason has argued one of the more reasoned oppositions that I've seen. His basic argument seems to be that the CFPA will not increase market competition and goes beyond historical restraints on lending. Zywicki believes that credit card debit is simply in substitution for other debt that consumers have always had, the CFPA will increase the cost of credit and that most consumers understand the products (See, Zywicki Testimony). I disagree with Zywicki on a number of points, particularly with respect to complexity of and transparency in marketing of financial products and basic fairness. I don't believe that consumers understand the terms offerred on financial products or even that lenders and banks actually disclose all relevant terms (c.f., FDIC Study on Bank Overdrafts). Moreover, without a regulator whose mission it is to take up consumer issues, there are impediments to regulatory intervention in products that are not as much on the Federal Reserve's top list, such as debit card overdraft fees. Nocera pretty much sums it up well: "The sooner we can pass the thing, the better."
Here's an interview that Zywicki arguing against the CFPA: