An AV ballot might look almost exactly like a PV ballot. Approval voting provides a better measure of popular opinion. Because AV allows voters more room to express their opinion, the election results provide a much clearer picture of voter preference among candidates, especially when third parties are involved.
Approval voting allows voters to vote honestly.
Also, approval voting, by its nature, makes it difficult to vote against a candidate, reducing the effectiveness of negative campaigning. Approval voting is intuitive and practical. Unlike some other alternative voting methods, AV is straightforward and easy to explain. In fact, if a voter was oblivious to a switch from PV to AV, he would still be able to cast a meaningful vote. While other methods may provide more fine-tuned options for voters, they generally place a greater responsibility on voters to educate themselves, and the risk of confused voters casting invalid ballots is high, and it is debateable whether more detailed ballots actually provide a better measure of public opinion.