HELP!! i'm buying a Mazda 6 need car people and Mazda owners?

[Baby Girl]

hi guys first of all i want to say thank you for taking the time to visit this. Well i just turned 19 and i'm buying a car as a present to myself i saw a 2003 Mazda 6 with 160,000 miles on it and it cost $3500 and yes the miles are a little high. I really honestly love the car and everything about it a friend checked out the car and said its fine well i'm a worrier and since this is my first car i want to get a great car that actually functions fine. well is there anything i should be concern with. I don't mind if i have to change some stuff in a couple of months but i don't want to buy a car and have to fix it up the same week too.