Absolutely, he is improving steadily but he isnt yet ready to immediately step into a Barca squad. I think people are being way too optimistic. Maybe it's because I watch him so regularly that I began noticing his flaws more but I think people are gonna be quite frustrated with a lot of things he does. He needs 2-3 more years to be truly world class.
I think that it's easy to predict that the most drastic growth/development in Dembele's game will happen when he is at Barcelona. Since that's the case, waiting might not really be that necessary. He's already shown his class in Germany and in the CL, not to mention his recent involvement with the French NT (a very difficult/competitive squad to make at 20). The likes of Isco, Koke, and even Thiago didn't see as much game time in the aging Spanish NT until a much later age than Ousmane is now, and he'll probably secure a more significant role within the next season or two.
He's a game-changing player and would be an immediate upgrade to our squad with potentially huge long term gains. His base skills are already very impressive at 20, a very complete attacking package. Imagine what can happen once he masters combination play with Messi/Neymar or when he really perfects his shooting ability in/around the box. His shot is already pretty powerful and he's almost perfectly two-footed. I think one of his main shortcomings at the moment is not playing to shield the ball during buildup. It shows too much to the defenders and can lead to players getting stuck/off balance on the dribble. Players who aren't that great at shielding are more prone to make errors under pressure; Neymar was often guilty of it when he first came here and wasn't that prolific/successful with his dribbling. I think almost all players improve at that to create space for passing/dribbling options once they really learn Barca's style of play. Dembele will start dribbling and passing with a naturally lower center of gravity as he learns and adapts.
Dembele and Mbappe have shown a lot at a very young age, more than most in their teenage years. I think I have to root against Mbappe though, because I know in the end what it'll mean for Barca if he actually turns into a once in a generation player. Hopefully Dembele turns out to be better
.