The original film almost achieves greatness, but faulters because of the horrible decision to add songs to it. It's pretty much the reason that Dahl disowned the film in the first place.
However, it's worth watching everytime just for Gene Wilder. It's such a masterful take on Wonka that it's hard to see anyone better it. The whole time you just can't get his character down, you really don't know where his head's at. One minute he's all joyful and fun, the next minute he wants to see what's going to happen to the fat kid in the tube.
It's absolutely fascinating to watch and Depp seems to have taken the character to another place entirely.
Oh and you don't have to worry about it being a remake. The screenwriter confessed that he's never seen the film before, but he did watch it after he was done with the script and he said he was surprised by 'how dark it gets'.