these are based on the US DVD sets that have been released, by the way. and Astro is definitely growing on me.
4. "The Sphinx" one was quite interesting- Astro runs out of energy and some eville men trick him into find a hidden cave to steal valuable equipment. he is only given small amounts of power so he can't fly away. I like the Sphinx character a lot.
5. "Cross Island" Dr. Sinister escapes and plans to steal treasure from Cross Island. another boy robot- Bobo- helps him. Bobo wants to be powerful like Astro, but things don't go as planned.
the animation isn't really that great- Hanna-Barbera was actually better at the time, in terms of fluidity. however, Tezuka makes excellent use of multiple panes to shoot through, giving the cartoon a great 3-D look (more spectacular in black and white as well) that US tv toons never got back then. that, and the inventive camera work really hide the animation "flaws".