Very enjoyable, maybe people are overselling it, but it's very nice.
I really like the opening cutscene, Wario in his car is fucking sick to say the least.
This game is Wario Land 2 and 3's gameplay at it's most refined. Trimmed out some things, threw away the garbage, and kept the things that made the game fun, while adding new elements too. After you "finish" a level and hit the frog switch, you're now on a timer and have to escape the level from the way you came in! Really cool and very interesting in some levels, like the lava one which turns to ice when the timer starts. You also have to collect 4 parts of a gem and a key ghost in order to unlock the boss and next level respectively. This game is more linear, at least compared to 3, with 4 full worlds consisting of about 4 levels, and then a boss. I'm not complaining, as it was an enjoyable time all the way through and it didn't feel like it overstayed it's welcome. They also gave Wario this new move, kind of like a bash but charges the longer you run, and can break stronger blocks. I don't really know much else to say, the levels were fun, once you found out each boss's gimmick they were fine, and the ending changing depending on how much treasures you get when you defeat a boss is fun.
The music is nice, especially the title screen, very good!
Just a pleasant time start to finish, and that's all that needs to be said.