The recruiting system has been acknowledged as being inadequate in its current form. Maybe change is on its way. Maybe complaining to MP's will speed the process up. That said, the thing for potential recruits to take into consideration here is that they are entering an institution in which complaining can be one of the worst things they can do, particularly if the complaint is made improperly. If, as a serving member, one were to skip links on the chain of command in order to piss and moan, then undesireable consequences would almost certainly follow.
Here are a few points for perspective recruits to consider on the topic of complaining within the military:
-Most often, as a new member, you are going to have unrealistic expectations. When those expectations fail to reconcile with reality, you're going to feel hurt, upset, offended, and hard done by. In some rare cases, the juniormost of personnel come up with a legitimate beef. Much more frequently, complaints from the newest personnel result from the fact that those personnel have a poor or incomplete understanding of the system in place, and as a result they end up feeling slighted even though that feeling is not justifiable. This is one of the things that new recruits just have to get over, and all prospective recruits should be cautioned that they're going to have to get good at sucking up BS in order to succeed in the military.
-The military has a number of official channels intended to deal with complaints. The avenues of approach for submitting complaints properly include the redress of grievance process, the office of the ombudsman, and to a lesser extent, the office of the padre. If you're going to complain about something after you've sworn into the military, you'd better make sure that you follow the process to the letter of the law, and that you have all your ducks in a row. If not, you will be subject to administrative and disciplinary action.
I can't see anything legally wrong with complaining to an MP of problems with the recruiting process, but mention of the word complaint by a prospective new member of the CF raises a red flag with me. Once you're in the military, civvie rules no longer apply, and if you're of the complaining mindset to begin with, then you may find your stay in the CF to be both unpleasant and short.