Overall a fun adventure, but it does have its share of problems.
First, the positives. Having Pikachu as a companion is really enjoyable and adds quite a bit of charm to the game. The dungeons are fun and offer a decent amount of challenge, something that some of the modern entries are lacking in. It's also really nice having Bulbasaur, Charmander and Squirtle at your disposal. It makes teambuilding easy if you want a simple, relaxed playthrough, but with the variety of other Pokemon around to catch you can simply choose to place the three classic starters in the PC and try something different.
And, the negatives. I'm not going to mention the graphics. This is a Gameboy release and technology was limited at the time, so I am going to give it a pass. Instead, my biggest issue is the battle mechanics. This is what makes me hesitant to continue playing. The biggest problem comes in the form of the sleep status and the move wrap. The issue with these lies in the fact that you are completely helpless. You can't attack until you either wake up or released from the wrap. You're essentially trapped, hoping for a chance to attack while the AI slowly beats your team. It doesn't help that being released from the wrap or waking up takes up a full turn.
While I enjoy the game for what it is, I would recommend Fire Red and Leaf Green over Pokemon Yellow. The Gen 3 remakes have nicer mechanics and more content to explore while still offering a challenge. Even so, this game is still worth playing on the 3DS if you are like me and want at least a taste of Gen 1 Pokemon.