As a junior, be expected to struggle with cold call, find your first client and reach the monthly goal. In addition, a junior would be expected to help the boss with some chores as well occasionally.
Be expected to get lectured by your senior/boss every morning, be sure to maintain high level of work ethics, which is not necessary a bad thing, but these could be slightly tough.
Eventually, sales is definitely not suitable for everyone. I think the pros outweights the cons, but I am just not suitable for this kind of job.