Design: Industry leading by a wide margin. I only have a few issues with the design.
1. It doesn't slide into your pocket as easily as all previous iPhone's despite being thinner.
2. The plastic between the glass and metal bands seems to be the weak point and is more apparent on the white model. It's the first place my phone has shown any signs of damage, and I've never dropped it.

Display: Amazing. Could it be bigger? Maybe a little, but I would rather have the pixel density and pocket-ablity and easy thumb reach.

Camera: I thought I got some good shots with my 3GS...

Reception/Call Quality: Great, once I switched to Verizon, pretty mediocre on Sprint however.

Performance: The advantages of Apple's closed platform is immediately apparent on this device, as all other iPhone's have been (especially at launch). The OS is incredibly snappy and fluid. Network performance is, in my experience, pretty average. On Sprint, 3G speeds were crap and sporadic and calling coverage was similar. The network made AT&T look great. On Verizon, I have much better voice and data coverage and everything is more reliable, if not ultra fast.

Software: Excellent. iOS 5 strikes a great balance between being totally intuitive and appealing to power users. I see no downsides whatsoever to the closed system. iOS is mature and very capable. Maps are a weak point I'm sure Apple is eager to fix. Google simply smokes Apple when it comes to mapping at the moment. I'm not a widgets person, so I don't care that Apple hasn't taken a more aggressive approach to them.

Siri: Awesome potential, but not as reliable as I would like right now. I absolutely want to see an API available to 3rd party developers, and I want it to have more hardware control. The great thing about voice interaction is it's impossible to visually overwhelm non-power users, yet it can potentially do a lot of work for power users. I'm glad Apple slapped BETA on it, however.

Battery Life: Honestly I haven't seen much improvement over my 3GS. It gets through a day no problem, but not if I get into an intense gaming session... A battery breakthrough can't come soon enough, but Apple makes the best of it given the performance and quality.

Ecosystem: Still the best. I have yet to see a practical downside to the controlled ecosystem.