Pro:

• High sustained damage with constant application of STATUS EFFECTS (100% chance)
• Very fast attacks
• Despite the low base damages, hits are pretty strong due to status application of CONDITION OVERLOADS (300% dmg)
  • Blast consist of two distinct status effect components – the normal stun on recovering victims which is displayed by the icon and the knockdown which isn't depicted – that can stack for additionally increased damage
  • Corrosive degrade 25% of enemy armor each hit (it stacks multiple times)
  • Impact useful against proto shields
  • Puncture is good against grineer armor, robots and some infested and the status REDUCE ENEMY DAMAGE BY 30%
  • Slash inflict TRUE DAMAGE and stacks multiple time
• Degrading armor will let your party members to inflict more damage
• Despite the short range, PRIMED REACH makes Lesion to hit at 4,2 meters

Cons:

• low critical hit and damage
• primed mods aren't exactly easy to get or cheap and [Primed Fury] is the hardest to get (200th daily reward)