Pros: Lots of 'em!
Cons: VLIDE isn't included. Kind of annoying how they did that. VSCODE is cool but I haven't figured it out quite yet. And since I was so accustomed to VLIDE my attention span for that sort of thing is... well... not great.
This really changes the AutoLISP landscape. Previously, you had to pay A LOT of extra money just to use AutoLISP, or use OtherCAD, of which many are good but you get lots of surprises when clients open their files in ACAD. For those of you that earn $$$ doing AutoLISP this gains you a lot of customers. This also makes DCL more relevant again. I was actually learning C# for a few reasons, one of which being access to richer dialogs. Since LT doesn't support .NET, DCL is much higher up the pecking order now.
Cool stuff! I just wish more people were as excited as I am!!