I've now managed to get my hands on what I consider to be a "benchmark" Prime (I won't mention how many I've gone through): that is, one that has no non-functional or clearly defective components and that performs as well as a Prime seems to perform at this point. My thoughts are as follows.
Regarding each major functional area, as I see them (in no particular order of importance except for the first two):
1. Screen: absolutely excellent. Great colors, extremely bright even without Super IPS+ mode enabled (which really does make the Prime comfortable to use in direct SoCal sunlight), good text, very sensitive touchscreen. A minor bit of light bleed on the right-hand side in landscape that's only visible on the highest brightness on black screens. No dead or stuck pixels. Overall, in my opinion the best tablet screen on the market, bar none. I'd rate the screen at 9.5/10 (taking a half point off for the mild light bleed).
2. Performance: excellent. No lag, apps open quickly and run smoothly. Gaming is excellent. There's an occasional hesitation in the browser (where it seems to hang for a second and then pops up a "Wait or Close" dialog), but I write that off to ICS and it's merely mildly inconvenient. I'd rate performance at 9/10.
3. Camera: decent to very good for a tablet, both still images and video. I'd rate the camera (relative to other tablets) at an 8/10.
4. Build quality: Excellent. No apparent creaking, good fit and finish, backplate is flawless and attractive. Nice and thin and light, very comfortable to hold for extended periods of time. I'd rate build quality at 8/10.
5. Audio: The external speakers put out excellent sound that's very full and rich for a tablet. They're not terribly loud, but loud enough for my needs (I measure that by whether the volume is sufficient for watching Netflix while I'm relaxing in the tub; and note this is for muscle relaxation--no bubbles or candles). Audio via headphones is clean and excellent. I'd rate audio at 8/10 external speakers (relative to other tablets), and 8.5/10 for audio out through the headphone jack.
6. Wifi: Wifi is not the strongest nor the weakest of the gadgets I've owned. In some places it performs worse than my Samsung Epic 4G Touch, in some places it performs better. I haven't yet come across a location where I need wifi, expect it to work, and it doesn't. I'd rate wifi performance at about a 7/10.
7. GPS: GPS on mine locks quickly when outdoors and connected to wifi, a little more slowly when not connected to wifi. It's locked as many as 12/14 satellites with 36' accuracy. Indoors and on wifi, it will connect to 7/10 satellites. In my car, it will connect to satellites and get a lock, but not maintain it consistently enough to serve as a navigation device. I'd rate GPS, therefore, at 5/10. It's functional for locating yourself when stationary, but not usable for navigation.
8. Bluetooth: Bluetooth devices connect quickly and perform well. Range seems very good as well. I'd rate Bluetooth as 8/10.
Note: I've noticed no significant difference with the Prime vs. other gadgets in terms of wifi performance when streaming to a Bluetooth device. For example, my Epic 4G Touch also drops wifi performance so significantly when streaming to Bluetooth that I can't simultaneously surf the Web on it. I simply do NOT think that the BT/wifi issue is unique to the Prime in any way, shape, or form.
Note 2: Some people have mentioned the audio lag when watching video and listening via Bluetooth headphones. My original Transformer and Epic 4G Touch do the same. I don't think that this issue, either, is unique to the Prime.
9. Microphone: The microphone works well enough for voice search, dictation (which is EXCELLENT in ICS), song tagging, voice recording, etc. No issues with it whatsoever. I'd rate the microphone relative to other tablets as 9/10.
10. Sensors: All sensors work perfectly, with good sensitivity. I've noticed that newer Primes (e.g., C1 builds) seem to have increased light sensor sensitivity and better automatic brightness adjustment. Overall, I'd rate the sensors at 9/10.
11. Dock: The Prime + dock combo is excellent, with reliable performance and great battery life. When closed and on standby, my Prime does enter deep sleep and battery use is <.5%/hour. When the Prime isn't docked, the dock loses exceedingly little power over time. I'd rate the dock as a 9.5/10.
Overall: I think the Prime is an excellent tablet that's priced well at $499 for the 32GB model. It has excellent performance, a stellar screen, good to great audio, and a superior form factor. Coupled with the dock, it provides extremely competitive battery life in use and in standby, and the best keyboard functionality on the market. It won't replace a notebook or desktop for complex document/image/video creation and editing and the most intense gaming, but works very well for just about everything else.
I'd rate the Prime overall at 8.5/10, with the majority of points taken off for the average wifi performance and below-average GPS performance. The Prime is NOT suitable for someone who wants to use a tablet as a navigation device, and may not be suitable for someone who needs to use a tablet in areas with only marginal wifi coverage. Otherwise, I think the Prime is the best Android tablet on the market, and if it Android has all the apps a person needs, the best tablet, period.