I watched GT's retrospective of the series a few weeks back to get hyped up for this series (although I ended up taking a detour to Ico and Shadow of the Colossus first), and from what I've seen of the first two Metal Gears, the switch to 3D seems to have done quite a lot for this series in spite of the gameplay still remaining 2D in essence.
Plus I've heard that Metal Gear 1 & 2 had much more shallow characters, story, and gameplay in comparison to the MGS series. I'll get the HD collection after beating MGS1 and at that point, the option to play through those and Peace Walker opens up. For now, I only planned on playing through the core 4 entries in the series.
...okay, as for MGS1, I actually sometimes (very, VERY occasionally) find some of the game's shifting camera angles to be a bit confusing. There was this one time where I pressed down on the control pad (for lack of a better term) to sidle against a wall, which brought the game into a camera angle where it looked odd that I had to press down (instead of up) in order to keep Snake's back against the wall. That was the only time this silliness happened though, and I'd much rather the game shift camera angles than not (again, one of the major reasons for how the move to 3D helped out this series in spite of the gameplay remaining 2D).
Also, there was another time where I died because Snake put his back against a wall when I didn't mean to do so and there were two guards attacking me. But then again, I know that I shouldn't be getting into situations like that!
I picked up some chaff grenades and a socom earlier but can't seem to use them. Not sure what happened.
On a side note, I've watched an LP of MGS1 before, but that was 2.5 years ago. Never watched an LP of any other game in the series, thankfully.
And yes I did recognize the main Shadow Moses gate (and the area's music!) from the MGS-themed Brawl stage. Brawl pretty much recreated it to a T other than those tall walls.