This was a difficult person for me to figure out how to rate. On the one hand, he apparently wrote such wonderful Stargate eps (can't speak for the non-SG eps in the credits list, btw) as (in no particular order) Ethon, The Fourth Horseman, Reckoning (generally rated the best ep of all time, and it's in my personal top ten), Fragile Balance, and Avatar (the only decent character development ep in all of Season 8).
OTOH, he apparently also wrote such abysmal eps as The Other Guys, Sight Unseen, Space Race, Grace, Chimera, and PU.
And of course, there are some normal-quality eps, like Icon, Citizen Joe, Cure, Memento...
But a rather surprising number of the SG eps in the credits list are either very, very good, or very, very bad.