1) No Bluetooth audio
2) No call waiting
Those are trivial. And those will likely be fixed when OS 4.0 comes out for the iPhone/iPod Touch and iPad. My experience was nothing short of a teenager's first time. First kiss. First drink. First whatever. It was very, very different.
Here's how I see it:
1) Generic SIP Audio = AM
2) Skype over WiFi = FM
3) Skype /w Silk Codec over 3G directly, = CD quality
This tells me that Skype has more than likely been working very closely with Apple to get the audio right. No hacking around with the built in iLBC or AMR codecs. Unh-huh. Skype went right for the main vein, the soundcard and figured out how to take the audio from the 3G signal media path, right to the audio output, and vice versa. And it sounds very, very good. How good? Well put it this way..why would anyone with an iPhone want to call over old AT&T after their first Skype over 3G call. Oh, and yes, it makes Skype on Verizon sound like, well, a plain old telephone call.....Ma Bell, you're back sounding like you're old self. The way the boys in the labs have always dreamed and said you could.
Now only if I had that working with Bluetooth :-(