IMHO, ~200mm is a bit long as a portrait prime, and is very limiting. If you're getting into macro then sure, it'll be a good, sharp lens. A good value macro lens.
From what I know in the Canon line up, the 85mm and the 135mm are the primes used for portraits. When you get to 200, you get into the sports category along with the bird watchers.
So yeah, keep reading up on it before you buy. Hope this helps.
I hear ya, and i agree 100%. Unfortunately, the Zuiko lineup doesn't have primes in the intermediate telephoto range. In fact, the only two prime lenses that Zuiko manufactures is the 50mm f/2.0, and the 35mm maco (i belive it has a minimum aperture of 3.5). Sigma produces three prime lenses, a 30mm f1.4, a 105mm f2.8, and a 150mm f2.8. They also make a telephoto 18-50mm with a constant minimum aperture of 2.8, but given the lineup, i'm a bit limited in selection. Again, i could always go for the $2000 35-100mm f2.0 (constant), but, i can't justify that purchase if i'm not getting paid for this.
I lean towards the sigma because it
A. Is cheaper
B. Also happens to be a macro
C. Is cheaper.
The Sigma runs about 370, whereas the zuiko 50mm f2.0 lens runs around 450.