The main advantage of pistols is that they suffer no accuracy penalty when your other hand is occupied. They're also fairly accurate, shoot very fast and fit the quickdraw (QD) slot. Pistols also suffer the least when being fired in melee combat (over 100% CQ Accuracy). The main disadvantages are: limited accurate range, lowish damage and reduced accuracy bonus from kneeling (just +10%).
We now understand how cased ammunition works and we'll be able to reproduce it, once we have a proper Workshop.