The hate is completely unjustified. The game was great, and took metroid in a good direction. Nintendo needs more story driven games and I feel that's what they were trying to accomplish with Samus. The gameplay was very fun and addicting, and the cutscenes were awesome. The story wasn't quite the best, but it was certainly better then the story we've had in the previous games. I do like the Primes more (because of all the side stuff) but Other M was a great 10 hour thrill ride.
The hate is completely justified for many reasons listed above. This games whole point was for samus to say, continuously "Hey, I'm a woman, and I have daddy issues." If the next metroid is anything like OtherM, I'll completely skip it, and so will most folks who actually played super metroid for any length of time. Team Ninja may have killed this franchise, just as Namco killed Starfox.
I do like the idea of more dialog and story in Metroid series. But the specifics of this story made up probably the worst video game plot abortion I had ever witnessed.
If you want to try out metroid, start with Super Metroid or Zero Mission on the GBA. Technically as far as story goes, Zero Mission comes first. The intro to Super Metroid summarizes Metroid 1 and Metroid 2 well enough that you can start on it, though. After that, play the prime series (Wii version with pointer controls. So much better.) Then play Metroid 4 for GBA (which is very linear, and more story driven). Then, if you REALLY want to see how bad OtherM is, play it. After playing through all the other games, it'll be impossible not to agree that it is by far the worst metroid game ever created.