Reading the manga doesn't get you caught up in watching all the anime filler arcs and you'll move along quicker to Shippuuden and have the full account of the previous story.
Yes you should watch it first because it shows the characters pasts which are really importand their strengths and weaknessed too, but after that all the important things are over which is when Sasuke and Naruto fight at a waterfall then I suggeast you move on to Shippuden trust me you'll learn a lot about the show :)
WELL,IF YOU WANT TO KNOW ANYTHING FROM THE PAST YOU NEED TO WATCH IT. THEN YOU WOULD KNOW ALL YOU NEED TO KNOW TO UNDERSTAND WHAT THEY MEAN. LIKE THE FACT THAT SAKURA AND INO ARE ENEMIES.OR THAT EVERYONE(BUT HINATA) THINKS SASUKE IS A TOTAL HOTTIE.YOU SEE MY POINT?