I recently tried out sela basmati. Sela is parboiled, Uncle Ben style. It is firmer and more rubbery and doesn't break as easily as regular basmati rice. It also lacks basmati perfume and the grains are slightly fatter and don't stretch quite as long as regular basmati. Its firmness is its only asset. Hence, it is useful in some specific sweet rice dishes in which the rice goes through multiple cooking processes but needs to remain long and intact. Some people recommend it for dishes like zarda pullao. Since it is tough and rubbery, some say it has a lower GL, sort of like pasta that is very slightly undercooked supposedly releases its sugars more slowly than fully cooked pasta. So I have seen it recommended for diabetics.
That said, I do not like sela for anything but dessert dishes. I tried to make biryani with it when I first bought it, and the rice never absorbed the flavor of the biryani gravy. It is definitely too hard for being a daily rice, either. So I just keep it for sweet dishes. Since it is Ramadan I made zarda once and mutanjan once with my sela. (I also bought a bag of Tilda Golden Sela on sale.) But when I use up the sela, I will probably not purchase it again, as I really don't like sweet rice dishes anyway.
There is nothing that beats high quality plain old basmati rice, definitely not sela rice.
In this other CH discussion, sela is briefly mentioned by me and another poster, GTM, if you want to have a look: http://chowhound.chow.com/topics/851085