How I Use It
I use this primarily as a tool to improve math fact fluency. The great advantage here is that practicing is fun and engaging. Students get to play others in their class, school, and beyond. They also get to collect money as they do it, which they can use to purchase items in the "store." The great advantage is that it can motivate students who otherwise struggle. The disadvantage is that its scope is limited and its usefulness is constrained to simple math facts and concepts.
Overall, I like the product and was willing to pay the price for a subscription. The advantage to Sumdog and other similar programs is that you always have a few kids who go home and do it because they want to do it. I am especially glad when it reaches those who generally struggle doing homework. You have to consider whether you think it is worth the money (about $200 per class), but if you are looking for ways to motivate students to improve fluency on basic math concepts, this may be a good option.