In 1621 and ten years old, he succeeded his father and became Grand Duke of Tuscany. Ferdinando III was an easygoing, agreeable boy who gave as little trouble to his tutors as grounds for hope that he would be much credit to them. Aged seventeen he went abroad on a continental tour, leaving Florence in the care of his mother and grandmother, neither of whom, perpetually quarrelling with each other and their council, appears to have either regretted his absence or to have welcomed his return.
He was not handsome with a bulbous nose, the fleshily jutting Habsburg mouth and the black moustache whose thick ends rose upwards, like arrow-heads, towards the soft and heavy-lidded eyes. He was rather fat and extremely good-natured, more attracted to handsome young men than to women, fond of hunting and fishing and of playing games like bowls, provided he was allowed to win, sometimes losing his temper when he did not win, a spectacle all the more disconcerting on account of his usual placidity and courtesy.
The people of Florence grew more kindly disposed towards him the better they got to know him. In 1630, when he was twenty, he and his brothers stayed in Florence throughout an outbreak of the plague, doing all they could to help the stricken people, while most others who could afford to do so fled the city.
His life-style was entirely without ostentation, yet Ferdinando was never mean. 

He spent as much on pageants, masques and spectacles as any of his predecessors; also, encouraged by his brother Leopoldo, he was a generous patron of scientists and men of letters. Ferdinando was selective and practical his main interest, apart from the experiments conducted by the Cimento, being the development of the Florentine craft of creating mosaics in 'pietra dura'. To contain his collection of ornaments and the family's ever increasing collection of
paintings and sculpture, Ferdinando was obliged to make expensive alterations to the Pitti Palace and to provide it with suitable galleries. These he had adorned with murals by some of the most accomplished artists of his time.
As a ruler, Ferdinando's policies were largely governed by a desire to avoid all trouble and unpleasantness. He was drawn into a brief war with the Pope's tiresome Barberini relatives, but otherwise contrived to face every threat fo Florence's peace and security with mollifying complaisance. He adopted the same placatory attitude towards the highly censurable activities of various members of his unruly family. He had no trouble with his brothers, Leopoldo and
Matteo, but Gian Carlo, a cardinal like Leopoldo, was a man of far less disciplined instincts.
Ferdinando II found his wife, Vittoria della Rovere, hardly less troublesome than Gian Carlo. She was a prim and interfering woman, plain and fat, who early on in her married life developed a double chin far more uncompromising than her husband's. In 1642 she provided her husband with a son and heir but this advent did not improve the uneasy relationship between them. Soon after the baby's birth, she found him fondling a handsome page, and for weeks she declined to
speak to him. When she decided to try to come to terms with him, he declined to be reconciled, and it was almost twenty years before their quarrel was properly made up. A second son, Francesco Maria, was born In 1670 he died and was buried with his father and grandfather  in the great baroque mausoleum at San Lorenzo.
 

"The Rise and Fall of The House of Medici", by Christopher Hibbert.