I've played most of the Metroid games; some good, some bad, a few amazing. This is one of the more original titles in the Metroid series. Morph ball and pinball seem like such a natural combination, it's amazing this hasn't happened before!
The good news is that there are a few boards that are primarily score based. These boards are inventive and have progressively difficult skill challanges. These boards are quick, and great for those people that don't have hours to invest per gaming session. The variety is cool: there is a spot where Samus changes out of morph ball and you get to shoot at some minor enemies. Some of the challanges are unbalanced, however. One of the enemies is able to grab and hold Samus and spit her out directly at the space between the paddles, effectively killing one of your turns unless you have a shield in place.
The bad news is the "boss" levels. You get one turn to try to kill an over-sized bad guy along with some metroid/space pirates minions to get in your way and drain your health. The minions can be affected by using the bomb function, but it is a clunky feature that feels tacked-on. The bosses are capable of attacks that not only hurt Samus, but drastically change her direction. Often the change of direction involves a flash, so that you can't tell where Samus is until it's too late to do anything about it. The frustration level quickly rises until you stop to go back to the first two boards.
Don't get me wrong, this is a fun game. It has its problems, but it is a good game. The physics work realistically; you can play this game without the tilt function at all (I did). In my opinion, there are not enough boards, but the ones there are fun, varied, and challanging. This is recommended for any fan of pinball, and you don't need to be a Metroid fan at all.
This game is great for road trips. It is always a great way to pass time on those long road trips because scoring big and not losing all of your balls in 10 minuies is fun anytime I say. It's also great because it's a pinball game you will never play. The unrealism of it makes it all worthwhile.