This is no small issue. While a non-/mal-functioning alarm on a cellphone may not seem like a big deal, it clearly is for those who rely on it. It may be a simple, common function for cellphones to have, but it does not make it any more acceptable when it fails to work properly or at all.
What may be the most annoying fallout from this, the second of the iPhone's alarm issues, is that people are not going to be able to trust the alarm anymore. If the issue was the alarm wasn't going off at all, all the time, under obvious and reproducible circumstances, they could issue a fix and it would be clear whether the bug had been corrected or not. However, since no one seems to be able to put a finger on who exactly this affects, why this happens and under what circumstances, when Apple issues a fix, there will always be that lingering sense of doubt in people's heads. There are some people for whom being late to work, for example, is a huge huge deal that just cannot happen. For these people (like my wife, who I just "gifted" my old 3G to yesterday and had the alarm fail this morning, all three of them), using the iPhone alarm is no longer a reasonable option.
To those of you who don't use the alarm function and don't think this is a big deal, that's because it's not... for you. As long as you understand that, there's nothing wrong with feeling that way.