It also turned out that FL's Sampler and 3xOsc aren't available to load into the Patcher. Hopefully at least the graphical and stability issues will be worked out in future updates, but for the moment you'd be safer sticking with recent FL Studio plug-ins only when weaving your audio magic, or waiting until the Patcher gets, well, patched.
So does FL Studio have everything you need? Not quite. There aren't many pro-sounding drum samples in there ready to go without some work - whether you're producing electronic music or otherwise, a solid third-party drum library would be a wise investment.
On the instruments front, there are lots of synths, but many are outdated (eg, SimSynth, FL Keys); and 'real' instruments aren't well catered for at all, so you'd probably need to invest in a few plug-ins and sample libraries in that area too.