Pros: Sound quality, bass, portability, durability.
Cons: No cons other than there are better options.
These are quite common in retail stores in my city (Toronto) and cost around $15-$20 CAD. I've been using them for years, because they are inexpensive, sound decent and are portable. They don't sound too distorted at high levels. I never had mines break, never had audio jack or audio cut out problems, but then again it really depends on the user, because I am very careful with my belongings.
Overall, these are great as replacement earbuds; a great inexpensive earbud for every day use instead of stock ones. Of course, there are better ones, but these are great for this price range.