-Often difficult to schedule hours that you actually want because they get taken so quickly. Also, they cap you at 6 hours a week (5 if you're probationary). This means you can only schedule up to 6 hours a week (but you can float however much you want). On Saturdays, whatever hours are left on the schedule, anyone can schedule more hours past their "caps." The problem here is the only times available are usually at 2, 3, and 4 o'clock in the morning--the absolute worst times to tutor for the average individual.
-Classroom tends to crash too often for my liking in the middle of a tutoring session, which can be very frustrating for both you and the student. They are very confidential about what information can be shared, so if something goes wrong in the middle of the classroom, often time you and the student will lose whatever you've been working on. In the event that you don't lose the changes to the file, you can't send it to the student. You can only send it to support and hope that they are able to match it to the student.
-Other sites make way more money. For example, instaEDU starts you off with $20/hr as oppose to Tutor.com's $11.50/hr. The con to this is that while instaEDU pays more, you can barely pick up a lesson to save your life! Tutor.com, however, has an almost endless flow of lessons available. So you do the math--$20/hr for 1 lesson a day at instaEDU (if you're lucky), or $12.50/hr for 5 lessons a day at Tutor.com.
-As others have stated, some students are rude and very unpleasant to work with. (Even with the worst students, I've never gotten a bad review, though). It's all about how you handle rude, difficult students. Stay positive, avoid the urge to catch an attitude back at them, avoid the urge to press "end session," use lots of happy face emoticons and often say things like, "I apologize for having such a hard time understanding what you're asking me. So let me get this right. You want..."
-When you log in, you have to be available for both live and asynchronous sessions. Sometimes, the business of your life might make you only available for an asynch session, but there's no option to toggle on or off live sessions. I feel like this is very unfortunate.