I bought the Forerunner 305 in May of 2007 and have been using it regularly ever since. I like all of the features the device offers and it sync's to my Macbook flawlessly. Coming with support software for Apple products is also a plus.
It seems to hold a good charge for hours of use. I usually do a 12 mile or longer round trip hike that takes me at least 8 hours and it never runs out of battery. I see that it would not have enough charge for an overnight or multi day hiking adventure and that could be seen as a negative for this product.
Overall the style is perfect for me. I hate wearing watches and never do, I have tried Polar and Suunto products and they always seem to make my wrist hurt. The Forerunner fits me perfectly. I forget it's on my arm until the heart rate alert goes off.