Really depends on where he lands IMO
This. This. This.
I think that Lamelo ball's game has matured since his high school days. He offensively I think he has way more upside than Lonzo, he has all the tools to be an elite slasher. His handles are already very good, he plays with an innate ability to sway defenders either on or off the ball. He also has very good court vision, it's not at Lonzo's level but because defenders have to respect his ability to score more or less anywhere within 20 feet it opens up the passing lanes. As such I think he has the makings of a good NBA Point guard at least from this standpoint.
BUT and these are major concerns.
His efficiency as a jumpshooter is POOR. Not below average, not bad but absolutely poor. His release is extremely awkward and he is going to need to work with a shot specialist at the NBA level because while he can slash and hit some mid-range shots, in todays NBA you need to be at least a 35 percent shooter from 3 and LaMelo isn't that infact, if he find himself open, if he's not going to go to the hole, he needs to pass at this point.
Despite being 6'7, his athleticism is nothing to call home about. He's not explosive and while he can outdribble some defenders, more pesky ones will try to sag off him and force him to shoot or pass, even better ones will try and go for the strip. But I think NBA level training regimen can help with that.
Last but most concerning the guy is a sieve on defense. He has the physical size to be ok at it but he seems disinterested in trying a lot of times and this has not improved. This will get exposed big time at the next level.
He's probably going to be a top pick because of his size and his upside, but where ever he goes needs to be ok with giving him 2 years before he becomes anything more than a role player.