You don't specify the exact model so apologies if I'm missing the point.
I've got a SZ4 MN_B. I suspect that this isn't exactly the same as the one you roadtested as it was considerably cheaper, and is I think slightly heavier.
I don't recognise the battery issues. I was disappointed to find that - in Stamina mode - but with the wi fi on, I only got 2 hours, or maybe a bit more than that. Luckily the guy in the store had warned me about the Sony "9 hours" battery life hype (I was looking at an even smaller model - but it promised 9 hours battery life.) He told me that this was assuming no programmes running and the display down to minimal. But even so, I seem to be getting considerably more battery life than you suggest.
I agree that Vista is far from great - and I'm glad that someone else is having the battery running down thing. I think it may be if you leave it in sleep. I find that if you put it into Hibernate and hang about for a minute to make sure that it's really turning itself off, you are OK, but it does often hang.
I'm moderately pleased with the model. It's hugely lighter than my previous Samsung X50, though that did have a truly massive screen, and it works OK, even if it took me a week to work out how to turn off the hugely annoying My Vaio start up programme - and another day or two to find the Vista games which had been deactivated!
Not the world's best laptop - but battery life rather better than your experience.