The plot, for starters, was nothing short of brilliant. The backstories of the main characters are fledged out sufficiently, without being too far fetched. Also, the plot may have its dark moments (observe the pwnage Zero deals out), but this is contrasted by its lighthearted comedic scenes (chase that cat!). Not to mention the Mechas. Ah, the Gawain.
The artwork, done by CLAMP, seemed a bit odd for a Mecha anime at first, but they proved to be a lot more fitting than I expected. Even the Mecha scenes were well animated, and kept the adrenaline pumping.
The music was, on the whole, alright. The BGMs were all quite standard, but in terms of the OPs and EDs, I only liked the first OP (Colors - FLOW) and the last ED ( Mosaic Kakera - Sunset Swish). The others were, well, meh.
The characters, however, were what really attracted me to this show. Lelouch, on his quest for vengeance against the Emperor, is starkly contrasted by his longtime friend Suzaku, who opted to change the Brittanian empire from the inside. As Zero, Lelouch has no qualms about using Human lives like chess pieces to carry out his plans, while Suzaku is completely against the idea of killing anyone (for now) (also, a walking contradiction, since he joined the army. Go figure). One of the highlights of the show was watching these two old friends clash on the battlefield. It adds a weird sense of realism to it all.
Overall, even if you watch it just for the Mecha action, Code Geass is a series that I highly recommend to anyone interested.
