From what I've read (and I'm doing this from memory, so be aware
), there is no final consensus on AL840001. I recall reading some learned opinions that differed from the opinion that what was found were microfossils, but instead had non-organic origins, and offered mechansims for the creation of the features found.
I don't have a professional opinion, but from the outside looking in, I would say that AL840001 was interesting, but because of these doubts, could not be taken as definitive proof.
It is possible (maybe even likely) that we will eventually find definitive proof of past or current life on Mars, and yet the features found in AL840001 will continue to be inconclusive.