Worms is a fun online game, but the single-player game is severely lacking.
Worms for the Xbox 360 is really not much fun playing by yourself. This is mainly due to the CPU A.I. being ridiculously accurate with every weapon in the game. After several challenges, they get horribly difficult to the point of frustration. This makes the single-player game annoying and not really worth the time it takes to go through it. There is no storyline tying all the challenges together or anything, so it's just worms on a map against other worms.
The multi-player is very fun, however. It does get a bit difficult to properly aim some of the weapons factoring in wind and such, but everyone has to deal with it so it's fair. And the game just oozes personality, as all of the worms have funny comments and sounds. There are even more maps and sounds to download if you so choose.
The game looks good for the type of game it is. It's not going to impress you too much, but the visuals never take away from the experience. At this point in the game's life-cycle, it can be difficult to find games online so that might be a big factor in any decision to purchase this as it is really only good when played with other people. But I would highly recommend checking out the trial version to see if it's something you could get into with your friends. It might surprise you, like it did me.