There are a few better five-eighth choices than Botha that haven't been selected yet if you ask me.
I have the 1986 Cavaliers tour on tape and Botha was pretty good in those matches. But he is unquestionably the most allergic player I have ever seen when it comes to tackling. The man wanted nothing to do with tackling. In all the games I saw I never saw him make one tackle. His best effort came in the 1st "Test" where Grant Fox ran at him and he pulled Fox's jersey, slowing him down enough to get tackled by a loosie (forget who) coming across in cover.
It wasn't so much a problem back in 1986 because teams didn't focus on hitting the 10-12 channel as much as they do now. These days five-eighths are required to do far more tackling. Also, Grant Fox stood incredibly deep in those days and really didn't attack the advantage line. I can't help but wonder how Botha would have fared against Mark Ella, who would always always attempt to draw the openside flanker and five-eighth into tackling him. I've seen a game Ella played against Ireland in 1984 and if you didn't try to tackle him, he'd take the ball as far as the advantage line, if not beyond. In that 1984 game Ella scored a wonderful try (handling twice) where the Irish five-eighth didn't try to tackle him. In my mind, Ella would have gotten the better of Botha.
As a kicker Botha was pretty impressive. In particular I admired his coolness when deep in his own 22. Every time he was under tremendous pressure his clearing kicks were phenominal. He possessed a beautiful balance that allowed him to kick off either foot with no problems. This balance also allowed him to drop-goals on the run, although for my taste he went for too many drop goals because he didn't succeed as much as I'd expected (considering his reputation as the drop-goal king).
But if I had to criticise him for something else, it's that his 1st, 2nd and 3rd instinct was to kick the ball, even when he was in the Caveliers 22. Occasionally he would spread the ball out wide and he was pretty good at it. But there was one moment I noticed where Botha kicked the ball ahead when he had an overlap outside of him! That was just Botha it seems, he kicked the ball too much.
For mine, he's not one of the 10 best flyhalfs ever, though he'd be close. He never made tackles, and I literally mean NEVER. And despite being a fantastic kicker, he kicked the ball too much.