I have a GoLite shell jacket, it's nice because it weighs practically nothing, so it's easy to throw in to your day pack and barely think twice about it being there, whereas I might not want the extra weight of my North Face jacket. However, it has no warmth, nor water resistance, so not very useful for when you need an extra layer most, and now lives mostly in my closet. I sometimes use it for cool morning jogs, or in summer day hikes where there's no worry of getting cold up high, just a little wind break if needed.
I recommend doing lots and lots of research before spending the bucks for GoLite. Read lots of reviews, see if there are other companies with similar products but more features. For instance, I absolutely love my MontBell light shell outer jacket. Barely heavier than the GoLite shell, but with a warm inner mesh, I was warm enough a few weeks ago on top of Mt Weart with a strong wind and some fresh snow. At 10 oz, it completely replaces a standard fleece jacket which are too heavy and don't pack well. And I remember doing lots of internet research to find and then buy that shell. On my next trip to REI I may have to look at some of their other products.
I also have a GoLite backpack. The top is quirky without a standard pouch, but part of why it's so lite. There is a front pouch on the bottom half to replace the top pouch. No padding on the hip belts, no lumbar support, no load lifters, this multi-day camping pack weighs less than most way over-padded day packs, and I must admit, I love the GoLite backpack. I use to get sore shoulders, not anymore. (or maybe I'm in better shape
) It's really nice for mountaineering when you dump most of your weight at the campsite, and you're not stuck with this almost empty heavy backpack to bag the peak with (or you bring an extra light day pack for the peak attempt, which is what I use to do!)