I might question the slab on its back, but other than that, the only faults I can find are petty, and are true of every Pokemon. It has weaknesses, it doesn't have all stats over 100, it isn't invincible. This guy is good. In fact, I expect to see him a decent amount. He gives Bug types the good name that they lost from the Pokemon I did a little bit ago.
EVs: Defense, Sp Def, HP
Stealth Rock: With not many Pokemon able to learn this, this guy becomes very important in that it has this great (I just shivered) move.
Toxic: With the defense this guy has, Toxic is a must.
Sandstorm: This guy has lower (not low, just lower) Sp Def, which Sandstorm takes care of while damaging the foe all the while.
Level Ground/Sand Tomb: Sand Tomb provides more passive damage in a form not affected by Taunt. Level Ground might force some switches, which is great for Stealth Rock, while also doing more damage.