Epictetus is by far my favourite of the Stoics I've read. The Enchiridion is short, acerbic, enlightening and funny. You don't get that much in philosophy, and I think that author clearly appreciates that.
That said, in the end I think Nietzsche is right in his criticism: Stoicism works, but it limits one's capacity for joy because to tools you use to combat negative emotion unintentionally, but necessarily, limit positive emotion.
I practiced Stoicism pretty seriously for a few years and it definitely improved my life, but once you've used it to build a solid emotional foundation, the Stoic tactics (which essentially involve always watching yourself for deviations from the Stoic path) limit your ability to experience extremes of joy.
There are elements of Stoicism (like negative visualisation) that are easy to integrate into life and are pretty much only positive, but for me, full-blown Stoicism is something I only bring out when I need to re-establish that solid baseline.