Fun little book. Well-written, easy read. The author portrays great visualizations with a minimum of text. I've hesitated getting the second book because they are each a bit short (or a bit pricey). But the setups here in this first volume could make for some interesting reading down the line, so I'll probably go read the rest of them eventually.
Death Zone was a fun read and a good value at $3.99. The ending is a cliff-hanger, but it's more a setup for the next story in the overall arc and didn't detract from the conclusion of this book. I wasn't able to really connect well with the characters in the story, nor their plights. I don't feel compelled to start reading the next book in the series, but I probably will at some point.
I enjoyed Gabriel's Revenge very much. Steve Umstead did a great job with imagery, both to paint a picture of each scene as well as to shed insight into the story's characters. The characters had a depth and realism that encourages the reader's emotional investment. The socio-political and technological background upon which the story was crafted was believably realistic. The plot itself had some nice twists, including my favorite plot device -- a coming full circle.
Gabriel's Revenge is one of the better books I've read from smashwords, and I definitely plan to check out the sequels.