Mildly strong. My favorite is 10 years old if that counts for something.

I have plenty of Nostalgia.  My favorite Kirby is Kirby's Adventure.  My favorite Metrodi game is still Metroid II.  My favorite Zelda game is still the original Legeld of Zelda.

However, like you, I still understand that later games have improved their formulas and are 'better'.  Heck, I can even make the claim that I like Ocarina of Time more than the original Zelda (a lot more) and I consider it the best.  It still doesn't change the fact that the original Zelda holds a special place in my heart (possibly because of that hard-earned mantle I spent 9 years on trying to beat it).

Likewise, recently Muramasa: The Demon Blade came out.  And for the life of me, I have gone almost 10 years thinking one game was the best 'Action/RPG Hybrid' game I have ever played.  And that was Symphony of the Night.  And yet after 2 playthroughs and endless internal debates....I still can't decide between my inner nostalgia (who has played SotN more than I can count) and this new game (which is quickly becoming one of my favorite games ever).

Nostalgia is a powerful thing, but I don't let it rule my life.  In the end, the quality and 'fun factor' of the game still wins out.

I wouldn't say nostalgia blinds me rather than my preferred enjoyment of 2D over 3D in some genres. I prefer 2D platformers to 3D platformers. I love the 2D action/adventure games (zelda/metroid type games)

I think NSMBWii is 100% better than Galaxy. Sure, Galaxy brought in new gameplay mechanics (which were a lot of fun) and had a "story" (which was a joke), but 2D marios are generally better than 3D mario.

However, KZ2, CoD:MW, Halo are all better than the awful goldeneye, which aged worse than anything I've tried to play recently. I guess the only thing that makes goldeneye good anymore is the great local multiplayer, which a lot of newer games lack.

I still hold my position that SMB3 is the best Mario game because of how it simply revolutionized EVERY aspect of Mario. The RPG'ish elements with the item boxes, the "world map". The flying, whistle usage, just about everything in that game did it for me. Although I make a good nod at Mario 64 for being one of the first TRUE 3D environment games and it did a good job at it.
I liked Zelda, but Ocarina of Time is the only one that I can go back and play without losing interest. Windwaker felt like crap to ME, and TP I felt was a step in the right direction graphicwise and some of the gameplay elements, but of course if they improve some gameplay later on and keep those graphics, it will be a powerhouse.
Surprisingly (or not) I see other games as superior to Zelda that I can go back and play again and again such as Brave Fencer Musashi. A game where they truly emphasized further on the day and night aspects even moreso than Ocarina. I like the final fantasy series as a whole but VIII is still my favorite (in fact, I am currently playing it).
Then I go back further in time and look at other true gems that I hold in higher regard than Zelda (yes NES comparisson), The Magic of Scheherazade. For those that never heard of the game, the dev made 4 or 5 other games that sucked and Scheherazade was the only good one they produced. iirc it had day/night elements (solar eclipses), when the eclipse would be active, winning at the casino was much easier, planting a rupia tree to make massive amounts of money, access to the greater magic, etc. Also time travel, and 2 types of battle systems, the zelda action adventure type an the turn based type, and you come across 10-11 characters (it's been a while but I know it's around that number), 3 classes, etc. Whether it's nostalgia's sake or the need to try one of the best rpg's out there I highly recommend you guys give that game a shot.
Chrono Trigger and Chrono Cross also remain one of my favorite games for all the elements they put into the genre (the amount of endings adds sooo much replayability. Finally more games that I believe is not nostalgia but rather quality are Shadow Hearts 1 and 2 (good gameplay, amazing story, breaks away from JRPG traditions in several aspects), Valkyrie Profile 1 and 2, which to this day I personally believe these 2 have the BEST battle system with alot of depth (Ar Tonelico 1 and 2 also get a good nod on the battle system).
Current games that I hold high are LBP, MGS4, KZ2, InFamous (despite the few glitches, the story is comic book worthy, and great gameplay), Demon's Souls (I am a masochist), Ratchet and Clank.

OMG I am blasphemous!!! I can't believe I didn't mention SOTN which I hold as the absolute BEST game in that genre and nothing has come close.

I highly agree with you man when comparing several 2D vs 3D games, SOTN, SMB3 are 2 prime examples. Granted I liked Lament of Innocence but it was no SOTN. KZ2 remains my favorite FPS, Halo has aged horribly for me although 3 did a good job to kinda bring it back for me. And yea on the golden eye comment man lol. BUT golden eye's local mp is something that I recently had so much fun with friends, along with perfect dark. Alot of current FPS' are forgetting how fun 4 player local mp really is and how much of a powerful selling point it can be. I mean imagine that on KZ2, or even a co-op with 4 player local mp, that would be king! hehe.

Sometimes I use Nostalgia to defend my opinion about certain games or systems that i see being under apreciated. Like saying "Yes, Sega Saturn was better than PS1, because *input games*". Not just but also to put that system or game in the talk.

About my Nostalgia's strenght. I's good until i get alzheimer i think (not soon i hope).

I also prefer MM to OoT. But nowdays i can't replay neither. I don't have the feeling of greatness that most of people have about both. :/

I have alot of strong nostalgia about my favorite games, but some of them hold up better over time and I'm willing to admit that. For instance, I can still play through and love FF VII today, but a few other games with very difficult mechanics are very trying, despite my love of them – Shining Force 3 or Lunar for example.

Hey man, have you played Valkyrie Profile 1? that game definitely stands the test of time and still the best battle system imo.

Yea, I didn't mention most of the games I'm thinking of. VP 1 is def among the 'masterpiece''/legendary' status of games.  It transcends gaming and is a true work of art for me. VP 2 was great as well, but the story did not have quite the same unique charm.