1) The first thing I noticed and thoroughly enjoyed was the quality of the full HD (1080p) WLED 300-nit screen. It is a delight to watch full HD videos in actual resolution. It is noticeably bright and has a rich color reproduction when I played Sony and Philips 1080p HD video demo clips.
2) Of course, the images of the laptop are all around the web; it is slim, sleek metallic and stylish. No plasticy feeling.
3) The built-in dual mic audio recording quality is exceptional. Clear crisp voice from the mic near the webcam. It captured even my whispers in Skype audio test clearly.
UPDATE: I found out that Dell XPS 15z mics comes with enhanced noise reduction technology (Andrea Microphone technology); the reason behind such high quality audio recording.
4) The webcam is also impressive. Even in low light, the performance was quite agreeable. The associated webcam software (Dell webcam central) was particularly interesting paired with Skype video call.
5) The back-lit keyboard is pretty good in sensing the ambient light and kick in the back-lit in dark surroundings. Useful upgrade from my older laptop.
6) Not much bloatwares pre-installed! 5 years back, I got a Dell Inspiron installed with all the crapware which slowed down the already crippled Windows Vista. This time, even Dell software asked for permission to install in this laptop.
Just Ok, but not so good (nit-picking)
1) No dedicated 'Home' button. Okay, one will get used to it.
2) No USB port on right side. It would have been convenient to have one at the right.
3) An easily accessible play/pause/mute button in the front would have been very convenient
UPDATE: (July 4th)
I found that there is an option to make dedicated media buttons in XPS 15z. Control panel > Windows Mobility Center (or use Windows Key + X). Then change the 'Function Key Row' option drop down menu and change it to Multimedia key.
UPDATE: I adjusted the volume and WavesMax audio setting at the Dell Realtek control panel. Now the sound is very clear and crisp without shrill. Yes, still it lacks appreciable base, but I do not expect quality base from speakers with such small form factor.
2) The strip of shiny rim surrounding the laptop is flimsy. I think it might come off sooner than later. I called Dell to check whether such potential cosmetic problem in future is covered in Accidental damage warranty and the answer was yes.
1) Blu-ray drive: I already raved about the high quality screen. But unfortunately this laptop cannot fully utilize the full HD potential since it can't play blue-ray discs.
2) Why the 3.5mm audio jack cannot accept the headphone/mic hybrid input? Apple users can use their iPhone headset on their MacBook ulilizing mic for video chatting/conference. How about Dell smartphone users? They can't use their cellphone headset with Dell laptops. May be Dell will implement that in next generation 15z's. My current option is a mic/speaker splitter adapter (Smartphone Headset to PC Adapter) for about $15. Something like
3) Option for a 128 GB SSD (since it might be cheaper than the current $560 upgrade cost)
4) Option for Windows 7 Professional/Ultimate
5) I hear that even better screen is there with XPS 15; Full HD B+RG LED screen would be nice to have in XPS 15z
Dell - Help Me Choose: LCD Displays
"WLED Versus B+RG LED: White LED (WLED) is the standard for most screens. It means that a white-colored light diode is providing the illumination for your screen. Blue, red and green LED (B+RG LED), on the other hand, means that there are three light diodes — one red, one blue and one green — providing the lighting for your screen. This provides a richer color experience."
Still to test: nVidia, Intel HD Graphics card benchmarking, Battery life, heating/fan performance on moderate to above average use (to test any issue of overheating on usual usage).