What are your opinions on the Ponziani?

People have been recommending me the Ponziani lately, so I want to know what are your opinions on it and how I should play it.

Best opening ever

It’s one of the best openings ever… as Black. As White, I’d highly recommend playing literally any other e4 opening. At least the King’s Gambit has enough prep and sharp counterplay that sometimes you can win in the opening. The Ponziani is just losing positionally after 3… d5 but Black doesn’t even need to know that to have equality, and White gives up all advantage or forcing play.

Can you guys give me example games on why the Ponziani is good/bad for white and black.

I think there are better openings. E.g. Vienna or ruy Lopez. In the Ponziani, you block the c3 square, where I like to put my knight, because on a3 it's too far of the game and d2 is only good in the middle game, because in the opening it blocks the queen and the bishop.

Well in many lines, your knight still gets to develop to c3. As well, because of the nature of the opening there is no rush to develop your queen side knight, so your bishop won’t end up blocked in as it will be developed before the knight in the lines where c3 remains blocked. As for your queen, it will almost always develop through the open diagonal created by moving the c pawn, so it will never be blocked.

After trying it out, I agree with RRamax

Check out this #chess game: C4ESXR vs cancuk17 - https://www.chess.com/game/live/145241806274

Here is an example from a game I played today: my opponent played 3. d6, the third most popular move. Then we reached a position my opponent was wholly unfamiliar with, and very quickly blundered the game away because of it.

Obviously most games your opponent won’t immediately blunder a piece and M1, but these are the types of positions that typically arise from the ponziani at our level. Where white has really good central control, good development, and a safe king.

At the higher level, your opponents will either try to take away your central control with 3. d5, or take away your king safety with the Vuković gambit 5.Bc5 in the Jaenisch counter attack.

If they play 3. d5, 4. Qa4 continues to add pressure. The best move for your opponent is the unintuitive Steinitz variation 4. f6, which will be matched with 5. d3, preparing for b4.

If your opponent plays the Vuković (never, I’ve had it once and they played the wrong sixth move) you must play Qd5 at the first opportunity.

i tend to be more sympathetic to offbeat openings than the average master, but ponziani is really a tricks only kind of opening. Once black plays the objectively best response (early d5, f6, and if bb5, nge7),white either must accept a passive equalizing response (d3 which is almost just playing the czech defense a turn up, or keep playing for tricks. 
Now if you keep playing for tricks, you may still win as the positions become very concrete and you will likely know the lines better than your opponent, but 2 or 3 losses to your bag of tricks and your opponent will likely prepare for a good 30 minutes to know exactly what to do to simply leave you worse or outright lost from every rematch on.
at best, if you someone that doesnt mind trading some objectivity for familiarity and the chance to bamboozle black , you can occasionally throw it at someone who you think may not fully know the theory and come out ahead nd worse case scenario, black equalized by move 6 , but it really is not an opening built for repeat performances.