The descriptive text reads like a middle schooler describing their 'cool and dark' PC. What else wields 'twin kukris' with 'deadly efficiency', has 'no compunctions about killing' but 'takes no pride in it', and 'doesn't typically deal congenially with others'?

6 monstrous humanoid racial hit dice make a decent chassis (that's still inferior to ranger HD). The ability scores are on the low side: +6 dexterity and constitution and +4 strength are nice, but low for a 6 RHD creature. Blindsense, a burrow speed, DR 5/bludgeoning, fast healing 3, and SR 17 are all at least occasionally useful. Alertness and Lightning Reflexes aren't the greatest bonus feats, but they're free. Finally, Harssafs have the fire subtype, which is probably a slight boost in overall power.

A harssaf's magical abilities are semi-useful. Flaming Aura means free fire damage on metallic weapon attacks and passively damages nearby creatures: don't stand next to allies and you should be fine. Please do not that by RAW the ability can't be turned off once activated.

Sand Pulse is a 1/day ability that deals some damage and blind creatures in a 30 ft. radius. It's not useless, but do remember that your allies probably value their sight before using it.

Finally, there's Sand Form, which is bad. At-will gaseous form gets a lot less interesting without the fly speed.

Considering everything, I'm not sure if the harssaf's decent chassis and reasonable special abilities make up for the six levels of lost class features. That said, I'll go ahead and assign a careful (weak) +0 LA here. Do discuss.