The stock hasn't made for a great buy this year, but is Vertex worth investing in for the long run?Vertex Pharmaceuticals (VRTX -1.71%) has a promising healthcare business with many growth opportunities ahead. But with the stock such a hot buy over the past few years and its valuation now hitting the $100 billion mark, has it become too expensive of an investment? Is it time for investors to consider other stocks instead, or can Vertex still be a good buy right now?Let's dive in and take a look.Why investor ...