Do you like it or hate it?
It's alright.^^
I think it's great for replay value. It keeps me coming back to unlock stuff.
I guess the only criticism I have with it is that some of the missions are like- nearly impossible to beat, and some are like- insane/impossible without a friend.
Luckily I have such a friend, and she is always willing to play..... though she just got Smash 4 for 3DS, and right now she's ecstatic about it, so HW will be overshadowed a little bit. Though we play both together. She doesn't have a Wii U though, so we just play together on mine.
I'm REALLY happy she got it too (smash), because now I can finally play with someone else! xD
Anyway, yeah, aside from difficulty level- which might not be an issue when I get my characters leveled up, I enjoy it just as much. It's a nice little tribute To the original, though admittedly, I never got far on that one. Without it, I'm not sure what else I'd do on it. ...Though I don't really understand the challenge mode. I haven't really tested it out much. I'll see what it's like one of these days... (I did run it once, but didn't do much and left afterwards- forget why)
But yeah, overall, Adventure mode is a good (and almost necessary) addition to it. I have my ups and downs with it, but that might all be resolved after I get higher in level. High enough to BLAST through tons of the enemies and missions that have gotten in my way before.