Planning on starting an affiliate website

Ok, I am trying to build a website like thisiswhyimbroke in a specific niche. What do you think?
Are websites like these still relevant and what kind of things I should consider and avoid?

It's doable but you got to think about SEO and how you're going to drive traffic. The reason traditional affiliate sites work well and are easier is because you can rank for terms like best x and x review etc.

Well proper research is always the best way to ensure the success of the website.
Try signing up for a free adword account and use their keyword planner tool to plan for a specific niche that you can explore into.
Try finding out the relevant keywords for your niche, and lookup whether the domain is still available for registration, and that will help with the site's traffic in the long run.
The amount of traffic going through the keywords would let you know whether anyone is searching that term - if there is traffic, you can definitely monetize that.

Off topic: Does anybody know of a WordPress theme that is similar to thisiswhyimbroke?