Personally, I think with Barkley you're probably going to end up with a slightly better version of Andy Dalton. Depending on your view of Dalton, that could be either A)Outstanding or B) Not as exciting as getting Smith or Wilson, who probably project to have higher ceilings according to some due to their physical traits.
Experience in the West Coast system, not elite arm strength (I define arm strength as the velocity on deep outs/comebacks, not throwing the 9 route. Different for everyone I suppose), not exceptionally athletic/mobile, looks down the field, usually goes through his progressions, doesn't do an impressive job with pre-snap especially taking into consideration his time spent in the same system.
I'll try to post an actual breakdown with times marked on the youtube videos with his snaps from this year and last year at some point if I can get a free weekend.