What can I say that hasn't already been said about one of the finest, best thought out, accessories in motorcycling?
The 'stich is a modern day legend among serious riders. Able to be worn year round, rain or shine, hot or cold, it's damn near perfect. If it has any flaws it's that it's pretty expensive ($700+) and that it's not totally rainproof. The latter isn't much of a flaw during summer temps, but when the temps drop you're going to need a real rainsuit. There are 2 problems: first is that even though it is Gortex lined and therefore suppose to be waterproof, even Goretex can't stop water that has a 60mph wind behind it from being forced through the pores of the fabric. The other problem is that the relatively large zippers on the pant legs allow water to seap by.
The biggest decisions to make when purchasing a stich is what color and 1 or 2 piece. I can't help you with color other than saying that the black material looks new even after a 100,000 miles of riding, I can't say the same about the red fabric. As for 1 or 2 piece, I recommend the 2 piece for several reasons.
While even the Aerostich people will admit that leather is probably better in the event of a crash, the material the stich is made of is a close second and you'll probably wear the stich more. It can't be beat for commuting - and anyone will admit a riding suit not worn offers no protection.