Naruto is a great series, or a horrible series depending on who's watching it. if your reading this review, you're trying to figure out where you stand on that scale, so hopefully this will help.
Naruto Shippuden is the follow up to the original naruto series, though you dont need to watch the naruto series to really understand naruto shippuden. The shippuden series certainly trumps the prequel, so if you are choosing one or the other, i recommend the shippuden series. However, if you watch naruto from start to finish (all 500+ episodes) you will find yourself crying, laughing and pounding your fist as the actions and drama ensues, which at the end of the day, is what makes this series so great, and if you dont watch the first half of the series, you may find yourself not really caring as much about each character.
The action is great, the creativity and diversity of the different ninjas and the talents they have make this series outstanding, you cant really help but be excited everytime a new ninja appears in anticipation of what moves they can perform.
The animation is executed pretty well, and it will leave you in awe as the ninjas dance across the screen.
All in all Naruto Shippuden has become a pioneer in the anime world, and anyone who doesnt watch this series is simply missing out. be wary of fillers, you can skip filler arcs (thats what i do) by looking online to see what episodes are filler.