I was surprised by the quality of the first one, where is expected a mediocre movie I got a respectable motion picture for the genre and the time, but this one, oh my god, even worse than what I expected the original one to be.
Except in some rare precious moments, the acting is terrible, very very bad, it's like the actors could not imagine themselves in the jungle with huge snake around them...
While their explanation about the size of the anacondas is OK, the concept of the flower blooming every 7 years doesn't make sense. If the orchid actually blooms every 7 years, they would make seeds which would probably start their cycle with one or more years of delay...
Plus they said they just discovered a sample of the flower at the start od the movie, but they knows exactly with no place for doubt when the flower is gone...

In a word, weak, easy plot, and no emotion.