A very glowing review of the Apex can be found here:
On Amazon and other places I've found a lot of favorable reviews along with some negative reviews by people who were dissapointed and misled by some overly optimistic marketing. There is no free lunch and you can't get super-bright light for 72 hours off four AA cells but given the current limits of technology, the Apex looks pretty good. I've been very pleased with my Princeton Tec EOS as a helmet light but it uses 3 AAA cells. The Apex has a more rational 4 AA cell battery pack and from what I've read it runs very nicely with rechargeable NiMH cells. The riders I talked to seem very happy with the battery life and light output of the Apex on the lower power settings.
I don't have an Apex yet, but it makes a very looking, compact light and I think I'm going to be getting one soon. If and when I do, look for pictures and a more detailed report here.