What can I say about this place other than, go see it! Really, it is fantastic!
We went on a ride on the Maid of the Mist (the boats that go up to the Horseshoe falls) and while I was expecting some tackiness, I was pleasantly surprised, no tackiness... It was just awesome to be on a boat not far from where the falls land and feeling the mist spray up (good thing they give out complimentary raincoats, we needed them!)
I now want to go to the falls down in Argentina (can't remember the name of them), and also to Victoria falls in Africa... Simply awesome.. I was seriously surprised out how much time we spent just walking along and admiring them... (don't even have the words to describe them)
If you head to Niagra, make sure you do stay one night (you probably don't need more than that), and make sure it's a Friday or Sunday night... As they have fireworks (better than 4th July in New York) on those nights... Got some gorgeous photo's of the falls lit up at night as well... They have some great big spot lights on the Canadian side that they shine onto the two falls so that you can see them so clearly... Ah, I could really see why so many regard Niagra as the place to go for a honey-moon. :-)