WRONG. I presented myself with a Sony 46Z4500 for christmas, and it has ABSOLUTELY NO LAG. There even is a special 'Game Mode' that cuts it down to an absolute zero (tested with the calibration option in guitar hero - 0ms), but even if you have it running on Movie Mode (including Motionflow 200Hz for a full 1080p motion resolution - something most LCDs, and even most plasmas can't do), the lag is still at impossible-to-notice 8ms.
Granted, the Z4500 is the second most expensive Sony model, but my mate has a W4000, which is over a year old by now, and considerably cheaper (less than half), and he has ZERO LAG as well.
In terms of picture quality, most new Sony LCDs are second to none - wonderful blacks, every setting customisable, great SDTV upscaling, and no clouding whatsoever (at least on my Z4500 - the W4000 has some slight clouding).
If you wanna know performance details, here are a very competent reviews on both the Z4500 and the W4500 (newer and better version of the W4000) - I did a lot of research before buying a TV, and this site helped me a lot with my decision.