In fairness, the "admitted liar" bit is a positive to most people I've spoken to. Realistically, most people are of the belief that most politicians are lying on a regular basis to start with; Abbott's stating of that fact was a refreshing dose of reality.
Of course, his political opponents have tried to label him as "Phony Tony" because of it, but from what I can see it simply hasn't worked. Particularly given that it's coming from political opponents who in the eyes of the public have reneged on implementing the lion's share of their own policy platform since gaining power. Calling your opponent a liar when the public sees you as liar isn't exactly a sound strategy for winning political points.