Looks interesting.
You may want some more boyz. A large unit of Sluggas and choppas instead of Skar Boyz unit/ killa kan, to soak up some shooting, but can still give the enemy a kicking when they get there.
Another option is some more longer ranged fire power, a unit of shootas with 3 big shootas in can be really handy at being able to give some covering fire. Always handy against fast enemies who dance round you otherwise. Rokkits are great, but are 12 inches less in range than a big shoota and fewer shots Rokkits have their limits. As a rule of thumb I give rokkits to close combat units and big shootas to support units.
But try your army out, see how ti goes. If you're mainly playing Marines it looks a pretty good list. It may struggle against Horde armies, like Nids and against heavy fire power armies, which don't take much armour/tanks like Guards can do, or fast moving fire power armies like Tau and Eldar, who keep dodging you until you run out of boyz.
But Waaagh like you're Green and give'm a good smackin'!!!!!