I finish mgs but it took me around 18 hours to finish i was that bad at game. Im wondering should i lower difficulty or will that take away from the experience?
Higher difficulties can take away some convinience features, make you use every bit of your equipement and increase the number of baddies while also increasing all damage values. Lowering it in general can reduce the number of sentries, increase the number of items you find etc. Haven't played the HD Collection but if it is anything like the originals than it should be like I've described in the first two sentences.
I'm pretty sure Peacewalker doesn't have difficulty settings, at least not in the traditional sense. For the other two its pretty standard, game doesn't get noticeably worse if you play it on easy it just gets easier. As with any stealth game there's a lot of trial and error involved on the harder difficulties (though in MGS4 you could do pretty well on extreme the first time around just due to octo-camo), if that's not your thing then don't bother.
I think, and correct me if I'm wrong, that lower difficulties make the game a bit easier. Harder difficulties, in contrast, will actually make the game more difficult. Like the O to confirm/X to back out in menus thing, it's one of those quirky deals with Japanese games.
If I recall correctly (which I may not), in 2 the difficulty level also changes how much ammo you find for weapons, and possibly some of the locations of the weapons (putting better ones early on). On a side-note, I remember when I played that game on the easiest settings the tranquilizer pistol always seemed to be a 1-shot instant knockout wherever you hit, which made it bizarrely more effective than the "real" pistol.
As far as I'm concerned, the "experience" of the metal gear solid franchise comes very little from the actual stealth gameplay and very much from all the nonsense surrounding it, so if you're finding the game heavy going I'd just turn the difficulty down. Though, I don't much like stealth games (and am pretty bad at them), so maybe that's just me.
You should be ok lowering the difficulty if you want, you can still tranq people like crazy and be stealthy if you want, or go Rambo and still have some fun. As other have said it just changes the amount of health, item spawns and some of equipment you get at the start of the game. The only major one is when you increase the difficulty and any alert is an instant loss and you have to restart the area.
I feel like the first two MGS games are already a bit too easy because of the soliton radar in the corner that tells you the cone of vision for guards. It was pretty tough playing MGS3 for the first time when you had to use other items to track when enemy patrols are. Man talking about MGS makes me want to finish that abandoned playthrough and start MGS2.
I'd say play on Easy/Normal (depending on how frustrated you're getting), then if you want to do further playthroughs then bump up the difficulty accordingly.
There's no shame in finding MGS games tough even on Normal (perhaps a tiny bit of shame in finding them tough on Easy :D) - they play so differently to other stealth/action games, especially MGS and MGS2. I think Drew is finding that out in the Metal Gear Scanlon series.