I'm writing a report about the advantages and disavantages of using microsoft excel, I'm not really familiar with excel so i'm a bit stuck on finding the disavantages... any ideas?

None whatsoever if you don't need it. But a wonderful tool if you need to organize things that could stretch to some serious data base .
I use it to organize ( by value and date) my gigantic stamp collection.
It's better to get clues searching the net Wekipidia is a place to star.

there isn't do you have?