It very much resembles previous releases. The one change I can really think of is to the weight meter, which is now in tons.
When Mothra needs discipline, you'll hear it beep and see it trying to tear down a tower. How you discipline a giant, multi-ton insect-goddess is beyond me, but it helps raise its justice meter. This has an effect on what character it will grow into. A higher justice meter level and better care will result in characters like Mothra or Fairy Mothra, while a lower justice meter and worse care will get you characters like Battra.
Multiple Mothra characters are available, and Godzilla and the Fairy Twins even shows up as secret characters.
After the teen stage, Mothra enters a cocoon, much like the Mori no Tamagotchi, but without the need to adjust the temperature. It's a lot like the Mori no, since both of them feature a cocoon stage and many insect-based characters. It moves faster than the Mori no, though, with no delay after hitting the buttons, and seems to change more quickly.
The game is a lot like the Mori no's as well. You have to guess which of four holes your Mothra is hiding in by scrolling through them with the left button and selecting with the middle button. You have to get at least three out of five guesses right to win, but getting all five guesses right raises its happiness by two hearts and lowers its weight by two tons. Very convenient!
The Mothra no Tamagotchi is good if you're looking for a faster-moving version of the Mori no, or are a fan of Godzilla and Mothra movies. It's easy enough to take care of, but not so easy it becomes boring. It has a fun, fast game, and a good sound, not too loud and not too soft.
It's a good Tamagotchi if you're looking for something with middle-of-the-road difficulty, harder than the Mori no, but not as hard as the Umi no
Mothra no Tamagotchi Character Chart