Kids love to see progress. Chess King has about 2,000 problems on 25 levels. The first 10 or 12 he'll probably whiz through, but then they start getting harder. Supposedly based on Russian training. Lots of overlap with Convekta products, but a cleaner interface. Pretty interesting mix of puzzles, tactical motifs, and mates. Unique is the game mode where you get to play Houdini at full strength. Won't you get killed, you ask? Oh did I forget to mention Houdini is missing pieces? Teaches beginners elementary mating with overwhelming superior material and intermediates how to nail down a difficult opponent after getting an advantage. They say the most difficult thing in chess is to win a won game so you get plenty of practice. Yep, when I get tired of serious study over here and just want something more relaxed, it's a favorite program.
Some hate the somewhat limited graphics, but I find them fine. Others want to be able to upgrade engines to something besides Houdini, but not possible. The database is better than nothing but doesn't offer the functionality of HIARCS or the far more expensive Chessbase. I use it daily.
On the other hand, why exactly is it that a grown man is worried about how to spend his virtual gold coins? 
My 14 year old son is about 1400 USCF strength. He has a diamond membership here and Chessmaster on his computer.
Would the Chess King software be beneficial to him? What would it offer him that he doesn't already have on Chess.com and Chessmaster?
Thanks, all.