A few of the things in my review have been covered by others already, but I wrote all this anyway so I might as well just post it. The first thing I would say is that Giant Robo isn't as bad as you might be led to believe. The second thing I'd say is that Giant Robo also isn't as good as you might hope. It is heavily dependent on your perspective, preference, expectations and experience.
Sure, it's epic and has plenty of action and drama and charm, but it's far from flawless. It's about as long as 14 regular episodes, and though I personally enjoyed it, I would not recommend it without several caveats. It's very up and down and hit and/or miss.
Story:
Giant Robo definitely has the feel of classic anime. Most of the recognizable staples are there, making it a good choice for an introduction to anime perhaps, but if you are an anime veteran, what may be considered classic by someone may come across as cliche to someone else. The story isn't bad, but not much about it is really innovative or unique. It has good foreshadowing and does a good job of gradually resolving mysteries in the main plot. However it also can be quite absurd at times, not to mention deceptive.
Most notably, for a show called Giant Robo, you would expect, well, more robots. Every episode teases you with this opening presenting different possible robo-nemisis but robotic combat actually plays a very small role in this anime. In fact, the robots are largely overshadowed by the characters incredible special abilities. Their powers are so fantastic, it doesn't really make any sense why robots/mecha are even involved at all. People can practically fly, destroy buildings, carry several tons of weight, and are ridiculously hard to kill. It makes the whole robot angle superfluous at best, and arbitrary at worst.
The overall plot is pretty good, it reminded me almost of Fullmetal Alchemist, and the twist ending is so ripe with irony it's almost redeeming. I really wish the story would've just jumped right away to and revolved around BF vs IPO. Unfortunately, the show gets really melodramatic and over-the-top towards the end which almost completely undoes its merits. There are also little annoyances like characters being able to talk to each other from unbelievable distances. The character's are extremely overpowered, especially the villains. It's a wonder the world isn't half destroyed from their conflicts and supersonic voices alone.
Did I mention at some point Robo cries? Apparently he was programmed for two things: to fight... and feel pain? There's nothing wrong with machines having emotions, it's a common plot device, but it's out of place here. He doesn't have steam vents to show when he gets angry, so not only is this inconsistent, but there's no possible logical reason for adding this feature.
The worst part of the story is probably how much they overplay Daisaku's importance. The way the character's bend over backwards for him felt really forced. Giant Robo isn't even the biggest or strongest robot really, he's just a big robot with something "unique." Their whole presence in the show felt like it was a token they were contractually obligated to include amidst the real story.
The ending is a mixed bag. Some parts of it are touching, surprising, and gratifying. The rest is just contrived and ridiculous. Some of it gets so cheesy your eyes may roll right out of your head. As if that wasn't bad enough, everything but the main story arc is left kind of up in the air. So after watching about a season's worth of episodes the end result is basically one big "To Be Continued..."
Oof...
Characters:
Some of the characters like Alberto or Ko-Enshaku or GinRei are kind of cool and central to the story, others not so much. Some of them had a lot of potential to be cool but most are just so sudden and random they aren't much more than cameos. With a few exceptions, the "bad guys" aren't even that bad, you almost want to root for them instead.
The tragedy in this is that it feels like they're trying way too hard to convince you Daisaku/Giant Robo are more important than they really are. I think I probably enjoyed them least of all. You could probably remove Daisaku and the few robots in it and have a better show.
The names are classicly generic. "So the Magnificent Ten are on the move again." Then there's "Big Fire" or the "Experts of Justice" and of course "GIANT ROBO." One guy might as well have been called Fingersnaps McDoom, it would've fit in just as well.
Art:
The mech design is very much like Big O, and the art's pretty good. It's bright and full of color and nice and clean for the most part. I'm not a big fan of the older anime style/look. Such as the tight modelesque Astroboy look or the weird long-nosed Cyborg 009 character designs, but something about this still felt kind of fresh.
Sound:
The music's also pretty good. I thought the whole orchestral sound fit pretty well and probably wouldn't mind having the soundtrack. The English dub is ok, and it certainly sounds a lot better than the older English dub. I still prefer the sub (of course).
