[youtube]http://www.youtube.com/watch?v=l4IHSda5Tqc[/youtube]
Tyreke Evans was considerably older than Booker and showed obvious flaws as a shooter and in terms of bbiq.
Devin Booker is the 3rd youngest 30pt scorer in NBA history. (Lebron and Durant).
Booker is the 2nd youngest with a point/assist double double in NBA history (Lebron).
Booker did it twice once without turnovers.
[youtube]https://www.youtube.com/watch?v=zKoSpsSoDs8[/youtube]
[youtube]http://www.youtube.com/watch?v=yxz8NjnAjqM[/youtube]
[youtube]http://www.youtube.com/watch?v=bddNclYumnc[/youtube]
Devin Booker has the 4th most 30 point games among teenagers in NBA history (Lebron, Melo, Durant). 2 more to catch Durant and Booker does not turn 20 until next seasons opener.
[youtube]http://www.youtube.com/watch?v=b19CQlEEnd8[/youtube]
[youtube]http://www.youtube.com/watch?v=Q6D988rbfPo[/youtube]
[youtube]http://www.youtube.com/watch?v=x99kcZWTqiI[/youtube]
[youtube]http://www.youtube.com/watch?v=KUvxlO1y5vI[/youtube]
[youtube]http://www.youtube.com/watch?v=0GYVi1Idzts[/youtube]
Booker has the 6th most points scored before age 20 ahead of Tmac and behind Lebron, Kobe, Melo, Durant and Howard.
Booker played 70 games as a teen so far, Lebron 108, Kobe 150, Dwight 100, Melo 82 and KD 80.

At the combine he posted the fastest shuttle sprint tome and the fastest lane agility time. His lane agility time was the third fastest recorded in the last decade.
He is also hardly scoring inefficiently. While his raw shooting numbers have dropped due to being the #1 option on offense plus running the offense and getting trapped and double teamed on most pick and rolls by now he is still shooting 43.1/35.1/84.1 which is more than fine for a 19yr old #1 option and better than Durants 43.0/28.8/87.3 as a rookie. Or for reference Russells 41.4/35.4/72.4 while not being the first option.
But of course for you it is easy to parrot what some people are saying who barely watch the Suns play.
Oh and Booker is among league leaders in drive efficiency (getting to the rim) as well as pick and roll efficiency. Last time I checked in January he was leading the NBA in PNR ahead of Steph Curry.
[youtube]http://www.youtube.com/watch?v=220m-VqkwdA[/youtube]

So yes a lot of what he has done puts him in absolute elite company.