I loved the Mystical Ninja game series growing up, so finding that there was an anime, and English dubbed no less, definitely caught my attention. I was a little disappointed the first couple of episodes, mostly because I was expecting a little more in terms of seriousness. I have to say though that this series will grow on you. It had much the same feel that Doraemon had for me. The whole kids can do no wrong sort of mentality. The good guys always won in this series, but it was still pretty entertaining. Once you can get past the whole little kid style of anime, you will find that this show has some decent things to offer.
One of the best things about this show is that you do not have to watch all 23 episodes in order. Each episode is independent of the others, with the exception of a few that are 2 parters. The only thing that is timeline sensitive is the introduction of some characters (this is to be expected of many series).
I did tend to find that the games made Goemon and the cast a little tougher looking, but I really think that the diversity in character development between different platforms and medium is an excellent way to branch into more audiences.
If you are a fan of ninjas fighting in a giant robot ninja who comes from blowing on a conch shell, then you want to watch Ganbare Goemon!