SPOILERS
On the first half of this episode, a swarm of mosquitoes led by a giant mosquito-girl attacks the city. She uses the blood drained by them to get stronger and evolve. There was a little fanservice here, but nothing to worry about.
I liked the gag that Saitama can't kill a single mosquito, getting angrier each time he tries. His face was priceless, and the 'fight' was great. Also, I liked that Genos (the cyborg) saved Saitama's life once, and them, he returned the favor, as bored as ever.
The second half of the episode focused on something that probably will be the mystery of the season: a crazy scientist that turns people/animals into cyborgs. And of course, he sends his minions after Saitama. Also, after seeing how strong Saitama is, Genos decide to be his apprentice.
More villains, and more fights. The second half presents us with more Saitama and Genos fighting scenes, now against some crazy animal cyborgs. I really loved this fights as they provided great action scenes and laughs.
This episode was even better than the first one, proving that One-Punch Man is on the patch to be one of the best anime of this season.
