Not sure about you, but their designs are definitely better than Cartoon Network's Transformers Animated.
Cover for Issue 1. Bumblebee's design is extremely loyal to his appearance in Generation 1
Although it's of a new storyline, Hearts of Steel seems to build on the story after Generation 1, where the Transformers who battled to their last bits of energy were forced into a state of hibernation and went through the Ice Age. When they were awakened, they found themselves in the Great Industrial Revolution, and they changed form accordingly to disguise themselves from the humans, and the story of Transformers in steam engines and vehicles begins.
Very much like the movie, Bumblebee is the first Autobots to appear in the comic. Since the comic is published before the movie, this should be a coincidence then?
Another huge feature of the comic is that important figureheads of the Industrial Revolution are among the human characters, for example Mark Twain the very humorous American writer, Jules Verne, a French sci-fi author who wrote Journey To The Center Of The Earth, Twenty Thousand Leagues Under The Sea, and Around the World in Eighty Days, and John Henry, the legendary black railroad worker who was rumored to be the strongest man alive at his time. Instead of fictional characters as we see in all other Transformers stories, I'm really curious as of how these historical characters can blend into Hearts of Steel. Don't tell me Jules Verne will go on a ride with Starscream in the comic, which will then give him the inspiration for writing Around the World in Eighty Days :)
Optimus Prime as the steam locomotive.
Megatron as the ancient giant cannon.
In terms of the Transformers, I think they are extremely well designed. Not only are they close to their original designs, but most importantly they look mechanical and robot-like. I have no problem accepting Megatron as an interstellar fighter jet, but I have a lot of problem accepting Optimus Prime looking like Superman XD. What do you think?
Unfortunately for Hearts of Steel, its release was too close to Michael Bay's movie, and to avoid confusion, the publisher decided to stop the release of more issues until the movie is over, but they did not announce how long will the comic be hibernated before the next release, now that the movie is indeed over. Hasbro on the other hand, decided not to do any toys from the series as well, for the same reason as above (but we all know they want to milk the movie's toys dry before moving on to another product line, agree?).
With the coming of the animated series next year, I wonder whether Hearts of Steel will be frozen forever?
Let's hope not.
All images from IDW Publishing.