Ah, the debut of Brock...He really was a lot different in his first appearance. His character has a much more serious and intimidating nature in this episode. Brock probably just lightened up as he traveled with Ash. I guess when you're a gym leader, you try to stay as strong and intimidating as possible.
This was a good episode. A part I particularly liked was when Ash refuses to accept Misty's offer to let him borrow some of her water Pokemon; this reminds me of when my friend was trying to beat the Pokemon League and I offered to let him borrow my level 100 Empoleon. He told me that he'd rather do it with his own Pokemon, and that reminded me so much of this episode.
I usually don't like it when gym leaders just hand the badge over to Ash without really defeating the Pokemon, but this one I don't mind so much. I mean, if you think about it, Ash took what was happening into his advantage. He was thinking on his feet.
The major problem I have with this episode, however, was the in the dub when they said Brock's mom died. And then years later, she appears well and alive, confusing many American fans of the show.