-Bad clients can be difficult and frustrating
-Some aspects of the company are not fair (ie. people with easy clients aren't always given higher quotas so they disproportionately win competitive bonuses)
-the company sets goals that are often much higher then client expectations, so a completely satisfied client does not mean you will be making more money.
-Work can be tedious.
-Some of the less experienced or overly competitive managers can make your life very difficult.
-IT problems are somewhat common.
TL;DR: I am enjoying my time here, but I have a good client and a good manager. I know people without those aspects who are struggling. However, most people are happy, and many people have used the company to jump start very successful careers in sales. The pay is also solid for an entry level position.