Switched from Windows to Linux 6 months ago, here's what nobody warned me about

Been using Linux for 6 months now, and I've gotta say, it's been mostly smooth sailing. But there's one major thing that's been giving me headaches - compatibility with my older peripherals. Specifically, my old external hard drive enclosure has stopped working entirely since I made the switch. I've tried to troubleshoot, but the drivers just aren't available for the Linux kernel. Don't get me wrong, this is totally my fault for not doing my research beforehand, but it got me thinking - how many others out there have had similar struggles with Linux compatibility? What kinds of quirks did you guys experience when you made the jump to Linux?