I'm not related to this in any way. I'll just say I paid the money recently and went through interview cake and it was really helpful. Learned a bunch and added a bunch of tools to my toolbox. Really liked the walkthroughs of problems bringing it from a brute force answer to optimal. I ended up making it to onsite final interviews with five companies in SF, which I will be going to in the coming weeks. Totally worth it.
Only gripe, the online ide you use sucks balls. Half the time I'm debugging whether I used tabs or spaces, and dealing with errors. No matter how careful I tried to be, it seemed to default to whatever I wasn't using and threw errors. Please get a new ide and add in some test cases that maybe tell me how I'm doing in those tests.
Otherwise seriously awesome site.