Philidor defense, good or bad?

There's nothing wrong with the Philidor. It's not great, but it's fully playable.
Right.

I've checked a few of your games. You don't really play the Philidor, instead you play something that starts like the Philidor and then you make a lot of bad and pointless pawn moves. This is a sure recipe to get into a losing position.
I recommend this:
https://www.chess.com/lessons/opening-principles

@MelvinGarvey
You seem to be a strong player, so I am sure that your lines and ideas are good. That being said, OP is a novice player, his rapid rating is below 400, so opening principles are good and a necessary start for him, especially if he just pushes the pawns in the opening. Of course when someone become a stronger player, it is evident that some knowledge about the openings you play is required to progress, but on 400 and even 1 400 level it will not be the deciding factor in 90+% of games. It is not really that effective for him to memorize exact opening lines as his opponents will likely play something non standard themselves.

I A Horowitz Chess Openings (start of the art to 1962) says:
This defence is designed to maintain Black's King Pawn on e5.
In developing consistently with ... Nbd7, ... c6 and ... Qc7, Black achieves a steady though cramped position. The older and incongruous continuation, ... e5xd4 however concedes White a distinct advantage.
From what I can see if the game goes 1. e4 e5 2. Nf3 d6 3. d4 then
3. ... e5xd4 looks to better than 3. ... Nf6 4. dxe5 Nxe4 5. Qd5
Well amusing is this:
as black threatens ... Bh4+

There's also the 5. g4 Philidor that black may surprise you with: (move order is not correct)
Perhaps a more sound move order:
Probably the most sound move order, although you need help from White to get there:
Here an illustrative Blitz game I played all recently, that shows the confusion and mislead of "opening principles" to White, leading them to trade d4 (like get some open file...), and then try to find some immediate usefulness to their queen's Bishop, by misplacing it on e3, when keeping it as a reserve force and looking for better things to do was the best idea.
32.. Qh3 Kg1 33 Be3# 😉

philidor is quite respectable but you have to treat the defense with the necessary respect it demands and study it carefully to get good results. ITs bad reputation comes from the fact that a lot of patzers who coudnt be bothered to learn theory use it to "wing it" in the opening.
I am especially fond of the Larsen variation (exd4 4.nxd4 g6!?) which in the past suffered quite a theoretical set back according to Bauer's philidor book but apparently engines now show you can play it via an early 5.nf6 with ng4-ne5 manuever being placed and often delaying 0-0 castling in favor of 0-0-0 if be3-qd2-bh6 is played early. (interestingly bishop going on b7!)
@darkunorthodox88 That's interesting, are you able to post a game that shows the Larsen variation with 0-0-0 by Black? thank you!

@darkunorthodox88 That's interesting, are you able to post a game that shows the Larsen variation with 0-0-0 by Black? thank you!
games? not really. this is just me comparing old theory with newer engine analysis. its very rarely played stuff so often its all you all have.
this is safer than a lot of opposite wing castle games where white's attack just seems faster. White is better of course but black has a decent position. White has no obvious breakthrough without costing him something.
If you need help, please contact our Help and Support team.
I liked philidor defense since i was a beginner, but is this good?