The amazing thing for me is that the Zelda franchise as a whole is so old and yet the quality of the games continues to impress.
I know people have their issues with certain entries, but I think each one has something to appreciate.
And now with Skyward Sword, it looks like we could get a great swan song for the Wii.
This is why I will always buy Nintendo systems, even if it goes into second-console status: their games, over the lifetime of a system, are worth it.
In fact, it's crazy that all three of their major IPs made the transition into 3D so successfully - Mario went from side-scroller to Mario 64 and was a breakthrough (and then reinvented itself as Mario Galaxy). Zelda went from overhead to OoT is still considered one of the finest games in gaming history. Metroid went from 2D exploration to FPS (or FPA haha I remember those debates) and put everyone's fears to rest.
Here's to 25 more years of Zelda.