What's led you to believe that? It's been 4 years and the Irish economy isn't looking too hot. I don't think 4 years is too early to call austerity a failure. If Mitt Romney thinks the US's recovery is anemic, I wonder what he'd think of Ireland's. Amazing isn't what i'd use to describe it though.
And just in case you say, hey, that GDP chart only goes to 2010,
Anybody that's interested in this stuff should read Paul Krugman's blog. The guy's been on the money for years.
http://krugman.blogs.nytimes.com/