I have not played either Metal Gear Solid game that came out for PS2 since their release. I purchased the Vita HD collection and I'm very happy that I did. First off, the updated graphics combined with the amazing Vita screen make for a stunning experience. While I expected to enjoy 3, as my memories of it were good, I was surprised by how much I loved playing through MGS2. I remembered not liking the Raiden section of the game, and I remembered being very confused by the plot. I guess the years have lessened the disappointment over not playing as Snake, and I was much more focused on the game, and enjoying it, so I wasn't just trying to blow through it. I had a ton of fun, and I now understand the convoluted MGS plot better than I ever had before.
Once I completed the two games I started messing around with the original Metal Gear ported from MSX. I had no idea that the NES Metal Gear was a shitty butchered port (source: the internet) because it originally came out for the technologically superior MSX system. Also that Snake's Revenge wasn't even a "Kojima Joint" if you will, and that Metal Gear 2 for MSX is the real sequel. I began Metal Gear, and have played up to getting the second keycard. Pretty cool stuff.
I'm super excited for Sony to finally get their shit together with PSONE games on the Vita, as I intend to replay MGS on it. I'm also going to start messing with some of the VR stuff on MGS2. I'm not promising I'm going to complete it all, but I want to check it out.