spec's spec's spec's .... realize that most people do NOT care ... they are most interested in 'day to day' user experience and in my personal experience nothing beats the mac so far.
Great keyboard, screen, thin, light, unibody etc it all ad's up to a notebook that's fun to work on, handle and enjoy.
The Z's keyboard isn't at nice, you have a sqatty 13.1" screen, the '09 Z I had was hot and loud and cheap feeling to handle, nothing like the MBP's we own. Then consider the ridiculous high resolution on a tiny 13" screen ... maybe good for watching movies, but not reading text ....
Ah, Sony just isn't it anymore, the Z isn't it, never was in the 2 or 3 that went through our office.
I'm simply stating the facts from our experience, I'd like to buy a thin/light windows notebook that provides the same great day to day user experience the mac's do ... but there's not one out there yet that satisfies us anywhere near the mac's ... so much so my company spent near $100,000 on Apple products in '09 ... that money used to go to Lenovo and Dell ...
Peace.
To each his own.
You have to admit though, that specs play a vital part in the whole equation of usability. Can you imagine a Ferrari with a pinto engine? It looks great, feels great, the seats are great, but man, does it take a long time to reach 60mph. You sit in the car and comfort yourselves by knowing you look great in it

PC's on the other hand are like japanese tuners, some look ugly, it doesnt feel right, seat are cheap but man can they fly.
The Z to me is like the middle road between these two extremes. Mind you I have recent Macs myself ( i own a 15 Alu and 17 mid 2009) But we have to admit they are aging. My 15 had 2 battery replacements and my 17 is due for a replacement battery.
Issues with my 15 (2007):
First one was returned because of a faulty motherboard
Battery expanded due to heat and was replaced
Yellow tinge on LCD
Creaks (understandable as its 3 years old)
LCD latch failure
Issues with my 17 (mid 2009):
First one returned due to stagelight effect at the bottom of the LCD
Very uneven backlight due to fans blowing onto LCD. IMO is a design flaw.
Glass peeling away from LCD
All is not bliss with Apple. I am sure this things are bound to happen with any other manufacturer, so lets not kid ourselves by saying Apple products are perfect.
Regarding the keyboard, how is the new Z's keyboard any different from a MBP? Both of them are in front of me and if i blindfold myself and use the keyboards, I wont be able to tell the difference. The have the almost the same travel and feedback. The 15 i have has the best keyboard among the three
Regarding the screen size, thats a personal preference and a point not to be argued. Its basically pointless bringing up size comparisons like "is a 15 better than a 13 or a 17?"
Regarding resolution, when is a higher resolution a very bad thing? Text can always be scaled, applications can be scaled with the flexibility of watching movies at full HD. If i had a 1440x900 how is it possible to view a full HD movie in all its glory. It is just not physically possible.