I rather like episodes along this nature, because unlike the later Johto/Hoenn episodes, this episode isn't anyplace near as contrived or redundant, nor does it artificially introduce characters and a new Pokémon, only for Team Rocket to try to catch it, for Ash, company, and their new friends to save the day, and then walk off into the sunset effusively (which an encapsulation of so many episodes later on - they're so predictable and linear, though I do feel that intercutting stories can dramatically reduce tension at select times). This episode just sort of allows the characters to wander about blithely and do their own thing - granted, it's very early on in the series, but still. I like that it's rather unpredictable and suspensful upon first watch. That gives it allowance for a greater notion of interest, adventure, and excitement in my eyes.
We alread know that Ash was about to attempt to capture Caterpie in the last episode, but still, the window of time in which he captures it, his hyperbolic reaction, Pikachu's reaction, Misty's reaction, and the way the "I got a Pokémon." Japanese BGM just kicks in and follows the mood.... something about the way all of those elements meshed made for both entertainment and stimulation. Everyone's so... carefree in this episode. In both the Japanese version and dub, as both Veronica and Rica have an admirable way of adding a firm range of emotion and building, strong tones to Ash's voice. Same goes for Rachael and Mayumi when it comes to Misty's voice. All of the voice actors add verve and stand in character (though, one could say that it isn't about characters or concepts being bad, so much as it is how they're used). I have to say, though, that Veronica's Ash is much, much lower in pitch in this episode than it is in the latter ones... his laughter remains the same, if not nigh identical, but she hits much lower notes in this episode... which still works just fine for me.
I do concede that Caterpie's prevalent victory and abrupt evolution was a tad bemusing in the context of things (especially comparing the anime to the games), but it's not the first time it's been done in a series, nor the last. I still feel Misty's and Ash's interactions, as well as the other character's and Pokémon, are intriguing in an episode like this, and this is the first episode where Team Rocket begin to lapse into the comedic villain role... which works, because it adds to their character and doesn't seem vapid and threadbare yet (by my view, they seem unique, and not just like any other set of villains). And outside of some glaring script discrepancies and inserts (when it comes to BGM as well if I'm not having a lapse in recollection), I'd say that both the dub and the Japanese version were great.
Overall, a great episode... the characters work well, as do the Pokémon, the battles, the plot... it's all in jest. But most of all, the resulting events of this episode aren't easy to predict (at least, to me).