I want to be able to make smooth motions, and i wanted to know: Is it succesful when it comes to cartoons that have voice acting? Also, is it simple enough to pick up in a week? If your understanding what kind of software I need and sinfig isnt great at completing my requrements, can you please recomend another program (would apreciate if it was free). Thank you 
Synfig can give you smooth motion. The quality of voice acting would impact the quality of your finished animation. Sync’ing voice to animation is not a strong feature of Synfig right now.
Like most things in life, you get most out of something when you put most effort in. Synfig can produce some amazing animation as you can see in the gallery or on Youtube. Will you produce that with in a week? Unlikely, unless you have previous experience in computer art or traditional art. You could probably pick up the basics of Synfig within a few days. To master it completely would take months. (I’m still finding features I didn’t know it had).
Chris
For lipsync you can use a free application called Papagayo. Synfig has read support for the output from Papagayo: http://synfig.org/ListImporter although sound support is not current Synfig strength.
-G