Even if you haven't watched the show, Harvey Birdman: Attorney at Law is still a fun, if short, distraction
Like other court, point-and-click games, in HB: AaL, you take the role of Harvey Birdman and are thrown into five cases he needs to solve. While they may start off trying to prove one situation, they branch out and you do get some really funny scenarios. The five cases are quite different from the last and involve a lot of interaction with various people and areas.
The cases are pretty simple. Gather evidence, then use the evidence to figure out the truth or to acquit your client. It's not hard to find the clues as each 'room' only has a few items to examine. Sometimes you might have to present an object to unlock something else, but it's fairly straight-forward and can be solved by anyone.
When you're examining the witness, you simply have to conduct trial and error. They do have restrictions and if you screw up enough you do lose the case, but the saving allows you to essentially avoid having to restart from too far back. Also, sometimes the evidence is so self-explanatory, connecting the dots doesn't take too much time. The reason why it takes 45 minutes to complete each case stems more from wanting to hear the funny dialog between the characters and the hopes of unlocking bonus content. If you are Street Fighter Fan, you might enjoy the cameos by members of that game. They don't add much to the game and even the games pokes fun at the connection between the game and Capcom.
While the game is both fairly shallow and pretty easy, it's still a fun game. The dialog as mentioned before is really good and memorable. Since I cannot compare the show to the game, for me the voice-acting is very good and the animation is really impressive. If people are turned off by other 'Court' games, the fact that this is essentially watching an episode of the program, might be enough to warrant a try. What would have made this game even more appealing would have been the inclusion of at least one or two more 'episodes' or more worth-while bonus content (eg. complete the game and unlock extra missions).
If you're looking at which version to get, I would recommend the PSP over the console version. The PSP version should be cheaper and playing on the smaller screen is a bit better than playing on your TV. It does load a bit slower on the PSP, but it's barely noticeable.
This is definitely a rental or a purchase for only die-hard fans. If you're looking for a good distraction game for a four-five hour trip and/or something to laugh at, then Harvey Birdman is a great choice. But if you're looking for a challenge and something that is deep you'll be grossly disapointed.