Should a former soldier have the rite to down the military about how his term of service was?

Timothy, my interpretation of the question you posed is: does a veteran have the right to do this vs. should they do it and how.  As I'm sure you know, an individual's free speech, etc. is protected by law, provided it does not violate certain criteria.  Now on to the more pressing issue of whether a veteran should bash the military (without trying to be constructive) after they leave -- my personal opinion is no.  I don't like seeing this happen, and a veteran sitting back and criticizing his old unit or old leaders -- when it's just for the sake of being critical -- often doesn't make anything better.

I find that the ex-Soldiers that bash the Army are most often those that had trouble with the Army values and/or Army lifestyle in the first place.  You will rarely hear a Soldier that had a successful career (whether that career be one enlistment or 20+ years) "bash" the military.  The junior CPT with a pattern of BCOM OERs or the permanent E-4 with multiple Art 15's has always somehow been wronged by their Chain-of-Command.  And of course, they would argue that Soldiers with successful careers just got that way because they kissed @ss and were "yes" men or women.  I think that attitude is just an extension of the growing attitude across our society that believes that success and happiness are somehow owed to them and not things that must be earned through hard work and dedication.  My two-cents.