i must admit that i did not follow didier after leaving us and i suspect its the same with most of the people here and this is where my doubt originates.
There was nothing much to follow

After Juve he took a 2 year break from coaching. Then last year he took over Marseille and immediately won them the league. And that was Marseille first trophy in the league after 1992.
Granted, he took over a solid team which was already one of the better teams in the country , but with the addition of Lucho Gonzalez, Diawara, Edouard Cisse, Mbia, Abriel, Heinze and Brandao, he made lots of changes and made them champions of France . He even made some changes which are (from what I read, though, since I didn't watch them much) considered as crucial for the success of the team. Apart from a new formation he also found new spots for some players. M'bia was a DM who was transformed into a CB and is now recognized as one of the best CBs in France.
if you say he did good in france, i will take that and believe you. the stats you gave look indeed promising.
I'm going by those stats too unfortunately. They do give a solid impression. At 35 (Del Piero's current age) he already took an average Monaco team to the CL final, by eliminating Real Madrid and Ranieri's Chelsea in the quarters and semis, before being beaten by Mourinho in the final. In the next season he didn't really improve, but managed to keep Monaco at the top and gave them CL place.
Then followed his Juve episode, two years out of football and a winning come back with Marseille.
Looks good and looks like he knows his job. Plus the youth is on his side. He is younger than Ferrara, but he already has trophies and success behind him, so we can't really make a comparison and fear his youth.
i wont say "france is crap and serie a is 10 times harder" since i do not follow the french league at all, but i have my doubts about this "deschamps would be the saviour in x-times better than ranieri, del neri, ferrara and zaccheroni combined".
lets just see what the future holds for him and us
Sure. People are sick of the latest failures so are looking for hope. Deschamps fits the bill, especially since he's an-ex Juve player.
But it can't be denied that his coaching career gives promises.