Well, I've kept out of this threat until now because I'm not sure the "has this show aged well?" question is all that relevant yet. Personally, I think it's yet another wank thread for Gundam 00 is better than "fill in the blank"/anti SEED patrons to just diss SEED yet again (and get replies back from SEED fans) and it's redundant at this point. IMO, neither the SEED or 00 Universes has had enough time time to really become outdated. In SEERAB case, the visuals still are quite fresh and the core elements of what pushed the plot (Genetics and the politics of where things might be going) are also still relevent. So are Gundam 00's similar issues with looks and outlook (that is, they are also still relevant and look fresh). They also both have solid music used in them. I'm talking background music here, btw - the OP /ED music wasn't really that wildly different, other than they were made in different parts of the 2000's and thus focus on different music styles popular during this period (both shows have both excellent and clunker OP/ERAB IMO).
So for me which show I like still comes down to which show clicked better with me, and it was SEED. I still think about SEED all the time where I haven't been able to make it through all of 00 (00 bores me to tears ). I want to know what Andy, Murrue, Mu, Kira, Lacus, et all have been up to since we last saw them, while I can't tell most of the lead cast of 00 apart. As to which show has the better mecha battles, this isn't something I dwell on. I like mecha, and mecha battles, but it doesn't make or break a show for me. This could be a reason SEED fairs better than 00 in my view. I can see/understand where 00 does have better, more well thought out battles, but for me it is like "who cares if I don't care about who is piloting them to begin with?"
As to the Space Whale, it has lead to one of my favorite thoughts on Anime and its fans, which is "Space whales and talking cats will mess with a Anime Fans mind better/faster than anything else out there ."
So there is my two cents on this thread .