These are helpful when you are learning the readings, potential meanings, and writing order, but they also assume that you know a lot of vocabulary and do not give a direct definition for the individual kanji itself. If you have experience in basic Japanese, than you should be able to look up the individual character in a dictionary or online and get a definition that way.
Overall, it`s helpful, but could be better. It is aimed for Japanese children in Japan after all.
This series of kanji training books is for native Japanese learners. Non-native learners may have a hard time catching up without the context presumed to exist. For those who need (relatively simple) exercises, this offers a good collection of self-learning exercises with answers for sufficnet feedback.