Although he's the best leader Labour have seen in 70 years (in part because he wasn't very Labour), he still wrecked the economy as Labour always does. It's just he took longer to do it than normal.
He inherited from the Tories an economy that was strong and growing, and instead of using the growth and wealth created to invest in our public services AND pay down our national debt, he did only the former. He allowed the worst Chancellor in living memory - Gordon "evil" Brown - to systematically steal from every pocket he could find, in order to fund this unaffordable spending spree. And when the easy tax increases were all done, he started on the devious and insidious taxes, hoping people might not notice or care ( (on his watch at least). Like ruining our pensions, selling off our gold reserves, taxing our energy and our holiday flights (FFS!) raising national insurance. Basically taxing anything that moves, so long as he could keep the base income tax rate the same and not create public outcry.
And then when the shit finally hit the fan with the crash in 2008, his incompetence was laid bare for all to see: We were completely broke after the decade plus of Labour profligacy.
Tories get back in, spend 10 years trying to sort it out again. Rinse and repeat. The only hope is they may get longer than 10 years this time, courtesy of our Trotskyist friend.