Reception is average, an improvement over past Samsung phones I've had. I've yet to lose service in places where they and other phones did (iPhone didn't work in one place where the Vibrant did at zero bars) and the bar meter/signal reporter is completely bonkers. -0dBm (no service) has no problems transferring data or holding a clear call.
I think people are associating it's lightness with how good or bad it's built and to be honest, it doesn't apply here. It feels extremely solid but also light. I did take note that the search capacitive button is slightly brighter than the capacitive buttons.
Screen responsiveness is off the charts for an Android phone as is Multitouch. VERY accurate on both accounts.
Calls seemed to be a bit bassy but that could've been the other callers because the last two I made had good clarity with a slight hint of tinny sound. Speakerphone quality is good, not as loud as the CLIQ for calls but sounds better overall. Not nearly as much distortion as you get with the iPhone or CLIQ when playing music.
I'll check tonight for myself. My friend is due for an early upgrade on Verizon in Oct. She should be getting the Fascinate (with flash) so I'll compare them.
TouchWiz 3.0 adds so many enhancements and completely beautifies Android in my opinion. The Music player is awesome, customizable EQ, some staging effects and SRS 5.1 Surround which admittedly, works better in other products. Definitely not SRS' or Samsung's best work. I use their plug in with iTunes, have it with my TV and car and they all sound much better. Samsung's Music Player still doesn't play Apple Lossless which is a bummer for me.
Putting the music player widget and a call widget in the notifications drop down is super convenient.
The phone is just snappy. The color depth when playing videos is super rich. Samsung (I think, not sure if this is a 2.1 thing) has added support for iTunes purchased video, and YouTube ripped videos. I'm forgetting the name of the codec used here but it's nice nonetheless
The Daily Briefing widget blows for Weather and News over the stock Android 2.0+ News & Weather widget.
The dialer is nice, improves the feel and look over stock.
TouchWiz 3.0 is just right for me, it doesn't feel as heavy as Sense and I like that.
Sound quality when playing music is awesome, way better than the 3G I just sold in my car. Not as loud (not too quiet either but this can vary with the playback source) but the SQ is much much better. The custom EQ and Wide setting has a bit to do with that though.
Overall, I'm impressed with TouchWiz 3.0 and what Samsung has done with Android.
I was going to do a video review of this but then I felt like people would be better off trying it out in the store to really get a good idea of the screen and other awesomeness Samsung brings to the table.