Can you tell me 4 Pros and 4 Cons about Plea Deals? They must be really useful reasons, someone's life is on the line

Of course the "benefit" of plea bargaining is that it provides certainty as opposed to the unknown of how a trial will turn out. If the trial is likely to go badly for the defendant (i.e. high likelihood of being convicted of the most srious charge and getting a long sentence) and there is an offer of pleading guilty to a less serious charge and getting a shorter sentence, then it could be advantageous to plea bargain. A trial (depending ont he exact charges) can be "all or nothing" - no middle ground. Sometimes a middle ground is beneficial enough to consider taking.