My father-in-law had one of the first fully loaded Daewoo Leganza's sold in Canada till mid 2007. He never had any issue with it. Just regular wear and tear expenses (i.e. brakes, battery).
GM still supports the Optra, so parts won't be an issue. Parts are reasonably priced and there are aftermarket options. If it's well taken care off and you can knock off $1000 off the price, its not a bad buy.