Usually "spirit animals" are used to bring out the best in people, and they often have traits that teach us lessons. If the tiger calls to you, then learn everything you can about the tiger and see if there are any traits you think you need more of in your life. Personally, one of the traits I see is free expression. The tiger has beautiful stripes full of color that no other animal has, so maybe you need to be able to express yourself outwardly more. This is just a thought, I recommend doing your own research.
There aren't typically disadvantages, that's the point of learning from animals. They have lessons to help you grow as a person. You also don't "apply" the qualities to yourself, you learn from the animal's qualities so that you may have them yourself. Your personality isn't a collection of stickers that you can take on and off.