There have been some posts from folks that really didn't like The Genuine Suzuki part # 990A0-70007.  I just installed one today on my 2008 and there are some things that are good about it.
1. It is made in USA
2. The brackets fit the bike perfectly, none of this "one size fits most" baloney.
3.  It is attractive and proportional for the S40.
4.  It does not effect the handling of the bike, like a larger windshield would.
5.  I have had windshields that when you take your hands off the grips, they start to wobble the whole front end, kind of like a trout spoon in the breeze.  This one mounts firmly and is stable.
6. It takes the pressure off your head and chest at 60 and above, for a less tiring ride.
There is a DOWN side:
1. Most dealers don't stock them and I had one on backorder for over a month.  Finally got new one off Ebay for $95 delivered.
2.  They are not tall enough for riders over 5'10".  I am that height and with the windshield mounted as high as possible, my forehead is in the turbulant air.  If I sit up real straight, this is NOT the one to buy. Top of windshield should be about 2.5 inches below your line of sight.  This one is about 4.
Result: It is fine for what it is and I would buy it again. You taller folks better keep looking.

Just got a national fly shield and this is my summer shield  

Turbulence hits me below my neck, head no longer bobbles in the wind.  Of course, got to close the face shield or I'm drowning in air.