Ajax fan from Amsterdam here. He's quality. Nothing like Frank de Boer was at Ajax.
Ten Hag is also not a typical Ajax coach. He never played for them and was schooled under Pep at Bayern. He made his name at Utrecht and was considered a gamble and 'not an Ajax manager' when he was hired. Too pragmatic and without the needed flair. He made his critics eat their words by turning Ajax into an attacking machine that took over Europe, while also instilling a defensive discipline and aggression that Ajax had lacked for a long time. He's also profession with the media.
Of course every hire from the Eredivisie remains a gamble. But Ten Hag at least should not be seen as a risk due to him coming from Ajax - he is a modern, flexible, pragmatic, attacking manager.
Don't expect Poch's charm and personality though, he is more rigid and serious.