We can't explain the universe, just describe it; and we don't know whether our theories are true, we just know they're not wrong. >Harald Lesch
Not a big fan of RAM disks outside of server environments, mostly because of the price vs benefit.
You have to take the RAM away from available system RAM, which means to have a reasonably sized RAM disk you'd need at least 24 or 32 GB of RAM (expensive!), most of which is reserved.
The biggest drawback is that each reboot you have to rewrite the contents of the RAM disk to it. This means that a short while after or during Windows boot opening programs or copying files will be even slower than without the disk, even for content that's supposed to be on the disk.
Then, given the performance of current SSDs, smaller programs already open instantaneously, not providing a benefit for those.
Also depending on how the software is written shutting down or rebooting the computer can also slow down significantly because the contents of the RAM disk have to be saved back to the hard disk.
Most of their use cases they claim to speed up are lies, too. It's pointless to create a swap file on a RAM disk to speed up CAD, browsing, video editing, etc. when you could store the data in your system RAM in the first place. Of course you need an application that is programmed to use large amounts of RAM, if available, but modern software usually supports that.
Additionally, the advantage of no wear is nonsense for cases where your number of (re-)boots + shutdowns is higher than the times you're going to access your data. Every boot it's mandatory to read the contents of the RAM disk from a hard disk and changes will be written back during shutdowns.
RAM disks are most useful when some time after boot you want to open a large program or load levels in games. And of course, which is their most common use, for having lightning fast access to a large data base which is accessed by tons of users.
There's a ton of freeware programs around that can create RAM disk as well. Example (no idea if it's any good):
http://www.softpedia.com/get/System/Hard-Disk-Utils/RAM-Disk.shtml#downloadAs a sidenote, RAM can be frozen and read out too, making data theft very possible if someone is commited enough.