My local Apple Store had them in stock so I swung by during lunch to have a looksie. Just wanted to see if the Iris Graphics made the UI any smoother-- and it looked pretty much identical to my current base rMBP from last year. Particularly, in scaled resolutions, the Mission Control animation was still a bit choppy. This is something that got WORSE on my own Macbook Pro after the Mavericks upgrade. Native resolution seems better on my laptop, and maybe incrementally better on the Haswell version, but something broken in Mavericks with regard to how scaled resolution is handled. Native res looked fine but no better than my current model which is also smooth. Scrolling in Safari seemed to be unchanged-- which is fine, it's already very smooth on my current rMBP. The Verge was still choppy in scrolling even on the Haswell model. No different from mine-- I think this is also worse under Mavericks than Mountain Lion. The model I test drove was the base 2.4GHz i5 with 8GB memory, and Iris Graphics with 1024MB. My current machine is last year's base 2.5GHz i5 with the 128GB SSD. After the test drive I decided have no reason to upgrade yet. It seemed the same weight and thickness as my current model, though if I had them back-to-back I would notice the incremental difference. Cliff's Notes: 13" Haswell rMBP looks pretty much identical to the previous gen as far as UI smoothness; meaning that any remaining issues are certainly SOFTWARE related and not hardware. The fact that Mavericks performs worse than Mountain Lion in scaled resolutions is a pretty big deal, which presumably can be fixed-- and having a faster GPU doesn't help at all. BTW I was also going to test a 15" model, but there was only one that didn't have somebody already using it-- and it had a dead SSD. Whoops!