The only reasonable justification to add Inside Pitch 2003 to your collection is if you want to play online against live opponents.
Out of all the baseball games available for the Xbox, Microsoft's Inside Pitch 2003 is the most disappointing. It doesn't come close to the other games in terms of fundamental play mechanics, available features, or graphical quality, and its only noteworthy characteristic is Xbox Live support, which manifests in the form of downloadable roster updates and one-on-one exhibition matches. Inside Pitch does have a few bright spots--it's the kind of game that you just know will be much, much better next year--but only casual players with an undeniable urge to play online should be interested in the game as it is now.
Regardless of how many baseball video games you've played in the past, you can't help but notice that Inside Pitch 2003 feels shallow. Hitting is purely a matter of timing. If you swing too early or too late, you'll probably hit the ball to one of the fielders in the infield. Swing right on the money, and you'll knock a base hit into the gap in center field. The concern here is that it's not too difficult to learn the proper timing, which means that even the worst players on your team will be clocking hits like Pete Rose or Ted Williams. You do have the option to swing for power or to aim your swing in order to pull the ball, but there isn't much reason to do either since you're already guaranteed success with a standard swing. Pitching is equally underdeveloped. Each pitcher has a repertoire of three or four pitches, and aiming is limited to 17 specific spots around the strike zone. This is enough variety for competition against CPU opponents, but it won't take long for human players to learn how to predict pitches thrown outside the strike zone.
A number of play aspects are just plain sloppy. During the pitcher's windup, your base runners will take off toward the next base right after you input the command, but if you wait until contact is made with the ball, they'll hesitate for what seems like an eternity. Microsoft came up with a great idea to identify a runner's quickness on the base paths according to the color of his nametag, but it's tough to benefit from this information when players refuse to advance. When playing defense, fielding is just as unresponsive and sometimes unpredictable. Similar to the problems you'll encounter with base running, fielders won't respond to a throw command until after they've recovered from catching the ball, which means you have to mash the button like crazy in order to execute tosses to first and second that would otherwise be routine. Following the ball is an effort as it is. Ground balls and line drives tend to die instantly when they hit the turf, and long tosses from the outfield will actually roll until they reach their intended target. There's a dive button for catching balls just out of reach, but it's best to ignore it, since players will often hurl themselves 10 or 20 feet across the field before coming up with the ball.
Even though Inside Pitch 2003 doesn't portray baseball as accurately as other games, it does have one feature that all the rest lack: online play. If you have an account on the Xbox Live service, you can pop into a lobby and set up a game against someone located anywhere in North America within a couple of minutes. Except for isolated instances, lag really isn't an issue. The action will stutter from time to time during long throws from the outfield, but that's about it. Playing against other human beings is much more fun than taking on computer opponents, mainly because the game's problems are easier to tolerate when both players are subjected to them. The online mode also includes the option to download updated team lineups, which you can use to keep rosters current throughout the season.
Other than Xbox Live support, Inside Pitch 2003 doesn't have a wide variety of gameplay modes. The season mode lets you draft players onto a team, perform balanced trades, and play through a full 162-game season--but that's the extent of your involvement. There is no franchise mode, so you can't do things like jockey minor league teams, negotiate player salaries, or experience the joy of following a team through multiple seasons. In addition to the season mode, the game has the usual assortment of exhibition, playoff, and home run derby modes, as well as a unique option called the championship challenge. The championship challenge allows you to participate in nine different events from the 2002 season, which you either have to reenact or alter in some way. Specific examples include breaking the 11-inning All-Star game tie, equaling Shaun Green's 19 total bases in a single game, and racking up Barry Bonds' 600th home run. This is a great feature, even if Acclaim's All-Star Baseball 2004 has twice as many challenges available in a similar mode.