Well, they had all the original cast except Walter Koenig, but including Majel Barrett. And they brought back guest stars like Mark Lenard, Stanley Adams, and Roger C. Carmel, as well as occasional others like Ted Knight and Ed Bishop. But most of the guest voices were done by Doohan, Takei, Barrett, and Nichols, although some were done by uncredited voice actors and a few by Filmation producer Lou Scheimer (who passed away over the weekend).
This is a myth. Roddenberry issued a memo in 1989 that basically distanced the canon from TAS, but that was because Filmation was going through bankruptcy at the time and Paramount couldn't make use of its shows. But once Roddenberry died, his definitions of canon were no longer binding, and Paramount/CBS resolved the copyright issues ages ago. There have been numerous TAS references in later canon works, like a mention of the Klothos in DS9, the various "Edosian" plants and animals mentioned in ENT, and references to Vulcan's Forge in TNG and ENT. TAS is included equally alongside the other shows on StarTrek.com's reference pages and on Memory Alpha, which limits itself to canonical sources. So there is no reasonable basis for the idea that TAS isn't canon. That was true for a couple of years, but that was decades ago.
Actually it was on a par with the rest of Saturday morning animation at the time, allowing for the tight schedule constraints the first season was under. Filmation's art may not have moved much, but it looked a lot better than what Hanna-Barbera was doing at the same time -- the drawings on Filmation shows were a lot less sloppy, there were fewer animation and coloring errors (because, admittedly, there was less animation), and the background paintings were much more beautiful. At the time, this was pretty much the best you could get. The only better-looking animation on Saturday morning was on the Warner Bros. theatrical cartoons that got endlessly rerun on The Bugs Bunny-Road Runner Show.
Not quite. At the time, in the early 1970s, most US animation was still produced in the US. The trend of outsourcing to Asia didn't begin until around 1980, give or take. It was in the '80s that Filmation became the sole animation house still producing its animation in-house -- although they did outsource once, with The New Adventures of Zorro in 1981, because they had too many shows in production that year to do them all themselves. On that one, they outsourced the animation to Tokyo Movie Shinsha, the best animation studio in Japan.
Another common misconception. Although the sex and violence had to be toned down for the time slot, in other respects the writers aspired to the same level as TOS. I discussed this just yesterday in this post in another thread. Compared to the other Saturday morning shows of the day, TAS dealt with substantially more mature subject matter. The reason Roddenberry went with Filmation instead of another animation studio is because they were the only ones who didn't want to turn it into a formulaic kids' show with teen sidekicks and cute alien or robot mascots.
