While doing this project, I've hesitated to link to any of Moebius' concept art for these films. Partially, I figure that most people know how to use Google and these images are pretty easy to find, but I've wanted to judge want makes it on screen more than what could have been.
But with Willow, I think it's absolutely a case of "what could have been." Moebius' concept images for Willow are striking, colorful and original. What is on screen is dull, muddy and unsurprising.
And sadly, it's those elements that keeps this movie from fully working. If the production had been better, so would have been the movie.
The plot isn't really anything new -- you have an unlikely hero in Willow (WarwickDavis) on a quest who acquires a few sidekicks along the way. Some are powerful, such as Madmartigan (Val Kilmer). Some are just annoying, like the Brownies. Most events are telegraphed in advance -- the audience is flat-out told that evil Queen Bavmorda's (Jean Marsh) daughter, Sorsha (Joanne Whalley) is going to betray her. And if you're thinking harm is going to come to baby Elora, you probably haven't seen a movie before.
In director Ron Howard's hands, the movie is overly deliberate and long. You know what's going to happen and basically how, so getting through it is a a bit of a slog. (It might be different if you're say, between the ages of 8 and 11, however. This may be exciting.) There are only a few inspired moments -- a wormlike two-headed dragon and the skull mask of the General Kael.
It does get a little more intense toward the end, but it never really becomes much of anything.
So really, it just leaves you with the idea that it could have been good. It could have been visionary (even with special effects that haven't aged too well). It could have been fun (even with uneven acting). Looking at Moebius' concept art, you see it could have been bright and weird and playful. Instead, it's just a by-the-numbers fantasy adventure we ended up with.