Twitter (TWTR) made its debut on the stock market today to much fanfare, and shares are already up big. Motley Fool analyst Taylor Muckerman isn't surprised by the news. What he is surprised by is just how much this IPO reminds him of Facebook's (META 1.95%), and he's afraid that Twitter will see the same results, especially considering that their business models are very similar. Twitter made over $1 billion in revenue thanks to advertising, but Taylor's not sure how the company will increase that -- all the changes he's seen from the company have been display-centric, and not focused on revenue. This is definitely one debut that investors should keep watching.