Assuming you are comparing the 13" MBP and 13" MBA, I think it makes a significant difference. Enough to be a key advantage of the MBA over the MBP IMO. Sure the MBP has better colors and viewing angles but unlike a higher resolution, it likely won't you make you more productive.
I agree on both counts. The MBA's display is more than adequate for virtually any real world use that isn't really graphics intensive. The lack of a matte screen is too bad, though, at least in my estimation. Before I got my 2010 13 inch MBA, I had used first a 17 inch Powerbook G4 and later a 17 inch MBP for a total of 7 years. Both had matte screens and I loved them.
This is pretty much the deal breaker for me too. I think the Air feels too light and flimsy but I'm worried that I'd miss out on the difference in resolution when it comes to watching films and photo editing.