Impact of the Emperors on the People

Arguments For

 * The emperors provided stability whereas the republic rarely saw peace
 * The average plebeian had little political freedom under the republic to begin with, so there was no real loss
 * The empire was more able to go for long-term goals, military conquests and construction projects were more carefully planned out as there was no need to race against term limits

Arguments Against

 * Maiestas (treason) trials under some emperors (mainly Tiberius) brought a reign of terror, the delatores tore Roman society apart
 * Augustus and Claudius were the only good Julio-Claudian emperors, the others were mediocre at best and totally apathetic at worst

Personal Conclusion
While some emperors had negative short-term impacts on Rome, in the long term the effects were positive as they brought stability and an ability to focus on long-term projects, and Augustus was one of the single greatest rulers in Roman history. The nature of a monarchical state requires the ruler to focus on long-term development of the country over short-term campaigns spurred primarily by greed, which the republic had (see prominent example Crassus).