The only problem is that this fabric has to be refreshed on a semi-frequent basis with a waterproofing spray. And there's always the old standby of rubberized raingear. There's nothing wrong with rubberized raingear, it just doesn't breath as well as other materials. A good hat is also a must. The majority of body heat loss occurs through the old noggin.
Some anglers prefer a wool stocking cap, while others favor either fleece or synthetics.
Last, but certainly not least, is footwear. For the blackmouth angler some kind of waterproof boot is necessary for launching and retrieving the boat. Waterproof boots are also necessary while you're in the boat. A couple of things to be aware of is the size of boot, and the sole. Don't use a boot that tends to be slippery on a wet deck.