Keep it strictly professional and devoid of emotion (if possible). Anything else will come off as sour grapes.
Despite all that, it's probable no action will be taken in respect of the points you raise, so it's worth weighing up wether or not you should bother raising anything negative at all (especially if you don't want to completely burn that bridge).
Despite all that, it's probable no action will be taken in respect of the points you raise, so it's worth weighing up wether or not you should bother raising anything negative at all (especially if you don't want to completely burn that bridge).