On the album reviews section for multiple bands, (ex. Whitechapel, Viscera Trail, Putrid pile), i've seen some reviews where they're not really giving a review, but they're more or less going on a rant. Now I myself have done this once in my review(s) & they have been approved.

I feel like every review I write I go on a rant about said bands or albums, but I think all I can do is go on a rant about them.

Can my reviews & other(s) reviews still be approved if I or others go on a rant about the albums or bands? Or will they instantly be denied because it's not a real review.

Describe the music enough and you are probably fine. Make sure you have read the review guidelines.
http://www.metal-archives.com/content/rules#tab_reviews