No real issues, just check that everything is as it should be. Check ALL electronics. Everything. Make sure every switch and sensor does as it should. Also get it HPI checked. Check chassis and VIN numbers.
You want to be thinking about cam belt as its getting on for 5 years old - ignore the mileage. If its got sunroof check it works and that there are no damp patches behind the sunvisors.
The only issue that Marea's seem to have is where the anti-roll bar moves laterally on its bushes causing a clunk over bumps. This is fixed by knocking it back then fixing something to the bar to prevent it moving. Some weld tabs to stop it. I don't have this issue though so it's not on every Marea.
Other than that there are no real faults. JTD engine is very reliable, powerful and ecconomical. Marea itself is a very attractive, practical car. Hope your find doesn't have any of the potential issues I've listed above.