For what he's worth, he's definitely a flop in the history of Barcelona's transfers. I still can't wrap my head around this transfer, less so than Dembele's.
A few goals here and there seemed to have been boasted excessively, due to his status of a player; the quality of the goals itself are often less discussed, which to me, are prominently lacklustre: often goals which are tap-ins, easy 1 on 1s, with little to no pressure from the opposition. The technique of his shooting abilities are thoroughly limited: mostly chips, lacking in power and finesse, one footed and of course accuracy. Poor conversion rate all around. Open play which invloves dribbling is where he struggles alot, often dropping deeper and deeper where the least pressure from opponents are, characterised by constant passing back, with no intention of driving the ball forward. Struggles with acceleration and gets dispossessed easily.
The main irony is that he is hardly criticised by some fans because of his low profile safe style which yield little mistakes, which in itself should be criticised because of his little to no contribution in attacking duties. This mindset conincides with the philosophy of former coach Valverde, which is to play as conservative as possible. Even if Griezmann were to be more bold, I doubt he would ever excel because he is simply not accustomed and equipped with the talent of a generic Barcelona attacker.
His stamina and workrate are of course, are undisputed with often many pointing out this attribute of his. If he were to be placed side by side with defenders or defending midfielders, he may emerge as on par. However, placed with some of the top modern attackers, notably strikers and wingers, he would be no where near.
The numbers during his Atletico days can cloud the judgement of his ability as a player, for me it's quantity over quality. But even so there was a steep decline in that over the years. Considering he hasn't turned up during Atletico's 2 CL finals, his goal against Barca in CL was offside, and hasnt really troubled Barca in so many years of La Liga, with stat padding against the easiest oppositions, just happened to win the World Cup with a overly stacked France team where Mbappe and Pogba stole the show, given the luxury of the free roaming main man role and penalty taker, I'm seriously doubt if he is even a world class player. He depends on his team alot where he usually just focused on tracking back and picking up lose balls, that in itself is hardly anything to shout about, at least in my book he is simply not good enough, where impact of great players and often change the game and come in as clutch.
He simply isn't that.