I personally like the SMBZ series. Alvin takes typical sprite animation and really pushes the limits of what you can animate with sprites. I love the effects used in the battle scenes, and the corny story is actually a bit of a drawing factor for me.
Some people hate the hell out of the series, but that's just their opinion. If you take a look at the some thousands of reviews, you'll see quite a bit of people beg to differ. It mainly depends on whether sprite animation is your thing.
If you love watching sprite movies, (A.K.A. Sprite T.V., Rise of the Mushroom Kingdom, etc.) then Alvin-Earthworm's series will have more of an appeal to you. If you hate all forms of sprite animations, and like to see entirely original graphics, then its not the series for you.
So, everyone is entitled to their own opinions, and you shouldn't give a damn if someone else thinks different.