Bill Hall's peripherals look a lot like Alfonso Soriano in that they're very strange. He flys out WAY more than he grounds out, strikes out a ton, and was still productive last year.
I'm still not very high on Bill Hall - he needs to prove his play style can produce good numbers over multiple seasons - there aren't many players out there with a ground out to fly out ratio as low as his last year (0.7 ish) and a batting average on balls in play as high as it was last year (.323).
These are warning flags to me at least - his swing produces a lot of fly balls, so the HR should come (although I don't see him as a 30+ HR guy) but a repeat of his .270 average is not looking great (he looks like a .255 hitter) and his stolen bases have dried up.
If you can stomach the streaks he can still be useful, but don't overpay for him in a trade.
I did a piece on him at my blog on Monday that takes his season apart a bit:http://blog.fantasybaseballagent.com/2007/06/11/whats-wrong-bill-hall/