Pros
Stable company, the job will give you good sales experience. Allstate generally has competitive products. Good place to get your life license if you are only doing property and casualty insurance. The public seems to know that Allstate is a good brand. It is second only to State Farm in nationwide production of property and casualty products. 2nd oldest insurance company in the US, which is a good selling point.
Cons
Being a producer at an Allstate agency for 3 different agencies within a year and 8 months, I can say that your experience at the job solely depends on the agent you work for. The agency owner is the King! (or Queen if its a woman) The agency owner calls the shots. He can give you a raise in a minute if he wants to. He can change your commission structure if he wants to. He can give you expensive online leads if he wants to, or he can give you terrible call sheets to repeatedly call, and then get mad if you can't make any sales from it. This much power the agency owner has bothered me a great deal. Also, there is no room for advancement unless you want to start your own agency, which is massive endeavor.