Well as they stated, the iPhone 4's Antenna system is better in that it receives a better signal in places where an iPhone 3G(S) might have a weaker or no signal at all. So in this respect, it is a better system. The downside to their system is that the "weakspot" is easier to touch and causes a dramatic decrease in reception when some people attenuate it.
Now I say "some people" because the people who are experiencing dropped calls while gripping the phone are in weak reception areas. This is why when that guy asked Jobs about replicating the signal issue with his Blackberry, Jobs stated that it only works in some areas----areas with weak reception. The Apple campus has their own AT&T towers on-site, so you probably wouldn't be able to replicate a dropped call on an iPhone 4 either.
I think that many users are angry about the fact that when they cover the band they witness their reception drop, though in REAL use, many don't encounter dropped calls.
Personally, I would rather have the iPhone 4's antenna system that achieves better reception in areas with weak coverage at the expense of having a weak spot than a phone with worse performance in those troubled areas of the network, because I can simple avoid covering that part of the antenna if it ever affects me.
That being said, when I cover the slit, I do notice the signal drop from 5/4 bars to 4/3 bars. I have yet to drop a call in real use though, and I only really drop signal when I intentionally attempt to cover this problem area to replicate the issue. It's not a problem that affects me in actual use.