However after playing this opening for some years, I have looked into the opening via the Moller attack and with the assistance of Stockfish made some interesting breakthroughs!!
Following one of the main exponents at the time Paul Keres an Estonian GM was one of the leading players for this opening. (A brilliant book I would like to add is, Keres Best Games of Chess 1931-1948)
Let's see the current opening main line theory; (Blacks move 13...h6 or 0-0 are the two main moves).
Lets see firstly 13...0-0;
1.e4 e5 2.Nf3 Nf6 3.Bc4 Bc5 4.c3 Nf6 5.d4 exd4 6.cxd4 Bb4+ 7.Nc3 Nxe4 8.0-0 Bxc3 9.d5 Bf6 10.Re1 Ne7 11.Rxe4 d6 12.Bg5 Bxg5 13.Nxg5 0-0 14. Nxh7 Kxh7 15.Rh4+ Kg8 16.Qh5 f5 Lets stop here position as below diagram.
However after letting Stockfish churn out the positions for some time with moves like 17.Be2 & 17.Rh3 it finally finds a breakthrough! Or you could call this a novelty 17.Qh7!+ assessing the position as dead equal 0.00. It seems that this opening isn't dead after all. Now Black has to play extremely carefully.
Stockfish evaluation as below;
17. Qh7!+ Kf7 18.Rh6 Rg8 19.Re1 Qf8 20.Bb5 Rh8 21.Qxh8 gxh6 22.Qh7+ Kf6 23.Rxe7 Qxe7 24.Qxh6+ Kf7 25.Qh7+ Kf8 26.Qh8+ Kf7 = 0.00! Equal, as below diagram.
Now I just wonder what a stronger computer may find in the position at move 17. Given that the final position is a draw and your White you may ask yourself should you be playing for a win? However shouldn't all chess games in theory be a draw?
13...h6 14.Qe2 hxg5 15.Re1 Be6 16.dxe6 f6 position as below
So I decided to look at the moves before this, taking it right back to Whites move 14 as Stockfish and I found an interesting alternative. 14.Qa4+ as below diagram.
14...Bd7 15.Qb3 Bf5 16.Re3 0-0 17.Nf3 Rb8 18.Nd4 Bd7 19.Ra-e1 Re8 20.Qc3 Position as below diagram.
if 20...Nf5?? 21. Rxe8+ Bxe8 22.Nxf5 + -
if 20...Ng6?! 21.Rxe8 Bxe8 22. Nf5 +=
Its also difficult to find any reasonable moves for Black to play here. Blacks best is some King moves like 20...Kh8 or Kh7 which naturally don't come first. The only reasonable move which might be played by a human over the board here is 20...b5 but Stockfish now only gives -0.25 evaluation keeping the position totally playable for White.
So in my opinion the opening Giuoco Piano is STILL very playable and a dangerous sharp weapon for aggressive players with White. I have only gone through the main lines, as I would be writing a book to cover all the side lines hope you enjoyed.