This movie was okay. Some scenes were fun and some were a bit boring. There are many characters to follow in this movie which makes it a bit chaotic.
The plot is very typical in terms of twists ultimately leading to revenge. "Collectors" is also a predictable title. Nothing new happened in it, so the film would be remembered for a longer time. Probably in a week, I won't remember that I watched it.

However, if you like this type of title and you want to watch something undemanding, you may enjoy this movie.

Also, Shin Hye Sun is perfect.