I'd recommend this book for any good tenchi muyo fan. The artwork is different from any style that I've seen and can be very beautiful at times. The humor can also be very cute.
However, I've rated the book lower because the plots bore me sometimes. The book, Mother Planet, seems to pull out problems from the middle of nowhere just to keep the plot going on. And, as far I can remember about this book, there wasn't any real point to the bad guy even showing up since they aren't very strong... or smart. Also, while I love to read shoujo manga sometimes, the "cuteness" can be really annoying... especially with Sasami. Ryoko is also a tad bit OOC, and in my personal opinion, a weaker character than in the anime. Dispite this, though, I'd still buy the tenchi series. This is a good series, even though it lacks some of the magic that the Tenchi Muyo anime did.
One other note is that this series is a relatively safe series. Any nudity they have follows the "barbie nudity" that the anime had. There are a FEW sexual jokes in there, but nothing that a 12 or 13 year old hasn't heard at school. All in all, the "No Need for Tenchi" series is cute, and beautifully done... just don't expect it to be like the anime it follows after.