I did the Paint/Epoxy Kit on my garage floor 2 years ago and so far it still looks perfect.
Prep is very important. I used a Muratic Acid to strip the old sealant off, then washed out the garage (very important to make sure you wash it out COMPLETELY) and let it dry overnight.
Another tip with a good Paint/Epoxy setup is to buy the pumice texturizer to mix in with it...makes it a bit harder to lay down, but it will keep you from falling and bustin' your butt when the floor is wet.
Also, as was previously mentioned, you shouldn't do this to new concrete until it's several years old.
Before-n-After pics below:
Before:
After:
