Getting away from the zero suit talk. While I would like a new metroid game of any kind and while I did quite enjoy Metroid II, I usually would prefer a new game always. I think Metroid II's biggest weakness is its linearity since it just makes it so easy compared to most of the other metroid games.
For an early Game Boy game, Metroid II was very ambitious, especially considering it was the second Metroid game ever made. Plenty of well-hidden paths, and it introduced many trademark mechanics to the series. You're definitely right about the linearity, but it still wasn't a dead linear game (area 3 was a huge labyrinth of four unique branches, and you had to travel down to area four before going back to explore area 3 completely).