Go Go Bunny Ears!
This is a solid Mario game with good platforming, much more in line with the series' norm than the first Super Mario Land. Enemies, fireballs, levels and general zone design with secret/extra levels make the game quite similar to Super Mario Bros. 3, and while jumping feels a bit stiff, the game's complexity is impressive for a portable.
The unique mechanic/power up in this one are the bunny ears, making Mario able to hover sideways and downwards pretty much as he likes. This easily leads to skipping large parts of some levels, or at least making some hard platforming bits way too easy. You could of course choose not to use it, but fact remains the levels doesn't seem to be designed for mechanic, making is overly powerful. Difficulty spikes way too far up in the end, making the last level a dull, long, repetitive chore, sadly putting a downer on the entire experience.
Pros & Cons
+ Quality Mario platforming
+ Impressive depth for a portable
- Uneven difficulty brings both boredom and frustration