Mass effect 1, less action than the other Mass effects but it is far better at conveying a story. Legendary edition fixes all issues that made the original almost unplayable.
Mass effect 2, great visual improvements and addresses some bugs but not enough. Having all DLC is definitely a boost. Still the best one of the whole series.
Mass effect 3, great visual improvements, but still buggy just not as buggy. Having all dlc definitely makes it worth playing. Did minor changes to the ending (very minor).
Andromeda, not here so huge boost.
Overall worth it because they totally fixed one, did necessary fixes for 2, but could of did more for 3. If u haven’t played mass effect I highly recommend. If u played mass effect and looking for a huge change pass. If u are a total fan of mass effect, u should try it.