I'm not really one for sports games. I typically like baseball and fishing most (not so much because i like either of these kinds of activities so much but because they tend to be some of the more popular genres from Japan, so I figure there are bound to be some decent titles for them) KGjr Presents MLB is not that much different from most NES baseball games i've played. You can do several game types such as single game or a season, an all star league. You can edit your team (though I don't know enough about baseball to know what i'm doing and its a clunky interface)
I was expecting some kind of arcade type gimmick like power meters or special moves but i wasn't able to discover anything like that in the single game I played. Batting isn't so hard. Home runs happen but they aren't to easy or common. Pitching stinks though its a pain to chase a ball (never was good at this part in video games)
The thought of someone looking up all the data and naming all 700 players to their real life 1994 counterparts just strikes me as insane. Did people really do that???

Game has some annoyances. It boasts of being able to customize and save 700+ baseball players names... but you have to name them ALL yourself, otherwise they just say #352 by default. I assume this means there is no titular KGJr to be found in the game (kind of common they liked to slap celebrity names on these kinds of games it seems, like Mario Andretti's Racing)
Overall I'd say its about what you'd expect, for me it was a mediocre experience, I managed to finish a single game, it gets a bit repetitive, after a bit.