I enjoyed Delphi's section most - leaping towards a group of enemies with turbo, setting them on fire and then slashing them down with the sword :D. Another combo I liked was the 'slow time' spell followed up with 'summon hail', hehe.
The first two bows are very weak compared to the guns you get as the meccs, so I hardly used them. The more advanced bows are good... but even then, sword and spells were a complete joy to play with.
Kabuto's section was alright - It was different, which was enjoyable, but a few elements seemed useless. The fact you have to order your offspring to do everything was annoying - they don't follow you or attack anything unless you specifically tell them to so I just gave up on them. Likewise, the horn-spearing thing - meant to be a way you can carry a potential meal and eat/throw it when you're in need, I guess, but I hardly used it as the animation takes valuable time you could be grabbing and eating the enemies that are causing you the damage in the first place.
My main problem with the Kabuto section was that I didn't really get a feel for the scale - you're about 100 times bigger than you are as a mecc but the viewpoint is the same so it's more like everything else has shrunk.
The ending was funny and it resolved all the characters' stories, but I don't think a comic game could compete with a more serious game in terms of a good ending - 'epic' will always beat 'funny' of the same quality.
The main thing that made giants stand out for me was the way it gave you three very different experiences as the three different characters, but each experience was genuinely *fun* in its own way.