Not sure myself, if he get's the players on his side and is given time then I think he could be just what we need. We already have alot of players in the squad that will suit his style of play. Fingers crossed it works out well, mainly because I'm a Spurs fan but partly to stick 2 fingers up to the Cheatski players & owner!
One bad experience doesn't make AVB a bad manager.
Just like blanking in a match doesn't make you a bad angler. 
Look at Brendon Rodgers,sacked from Reading did well at Swansea and now the Liverpool manager.
AVB has won a few things
Primeira Liga (1): 201011
Taa de Portugal (1): 201011
Supertaa Cndido de Oliveira (1): 2010
UEFA Europa League (1): 201011
Awards and achievements
CNID Breakthrough Coach (1): 2010
CNID Best Coach (1): 2011
Globos de Ouro Prmio Revelao (1): 2011
Records and trivia
Youngest manager ever to win a European competition.
Porto record for the most unbeaten matches.
Most wins in Europe in one season by a Portuguese club.
First manager to go unbeaten in one season in the Primeira Liga in the twenty-first century.
I hope he does well and has learned from the mistakes at Chelsea.