SERP Analysis gives tons of useful data, I think it's my favorite one as I can plan strategies based thanks to it. Keyword Tracking is also an amazing feature together with Rank tracker. Review collected by and hosted on G2.com.

Its not a big issue but imo web version of the app for mobile devices could be improved even if you have a dedicated app for ios/android devices:) Its just expected for such a useful tool to be more responsive on mobile devices without installing an additional app. Review collected by and hosted on G2.com.