I love this film, seen it many many times. At a comic convention in 1986 I got to see it in a theater setting with Bakshi there so that was cool. The rotoscoping here is more like that in Heavy Metal and it is not rushed or distracting, in fact one of the scenes the abduction of Tigra is done in slo-mo and is particularly effective. This film exhibited I think the full potential of that much maligned technique, and one that I might add would be resurrected in later films such as Waking Life
using computers instead of physical animation and hailed as "innovative"
While many detractors have commented on the rather basic plot it was written by Gerry Conway and Roy Thomas who wrote most of the '70s Conan the Barbarian, and Savage Sword of Conan comics for Marvel so it had a long pedigree in fantasy. It is certainly a more adult oriented fantasy film, but one that is not gratuitous considering who the director was. One thing hinted at but never elaborated on is that Darkwolf is Necron's father, the scene where this is revealed hit the cutting room floor.
The pairing of Bakshi and Frazetta was something special, and even James Gurney (Dinotopia), and Thomas Kinkade (the Painter of Light) were background painters on this. I talked to James Gurney once and he told me that when Frazetta would visit the studio all he wanted to talk about with the animators was hot dogs and baseball
Robert Rodriguez is a huge fan apparently and is set to make a live action version which Frazetta himself wanted to do.