After buying and reading Hellsing in the hardcover edition, I felt that this series is very average. I have two major issues with this manga. Hellsing is an action manga, there is really not a lot of plot, the majority of the manga are action sequences. A good action manga usually needs some kind of character development. However, this manga does not have a lot. The main character Alucard is the most powerful character from the very beginning of the manga, he never met any real challenges throughout the manga. Thus, there is a lack of excitement when he wins. The only character who has some development is Seras because she is a new vampire.
Furthermore, I had some issues with the panel layout. Some of the action sequences are very confusing to me. There are times when a battle finishes, I don't really know how the battle is won. Going back to reading it again still doesn't help. I had to guess what really happened. The power of the characters was very abstract, there is not a lot of explanation, and I had to use my imagination most times. In the end, I felt this is a mediocre manga. People who read this as a kid might feel differently.