Snapshots are not particular tricky, but they are often misunderstood, on both the hosted and the VI side. (I just had to clean up a huge Fusion snapshot that was really difficult — I tried to commit my snapshot (merge it back into the base image) by deleting it, but I didn’t have enough space left to make the new clean file. Oh well, I didn’t need those iMovie files anymore.)
People sometimes get confused about how snapshots work and how to use them. While snapshots are incredibly useful for many things, one major misconception is thinking that they are a form of backup – they’re not! If a lightning strike totally fries your computer, a snapshot won’t help if it’s on the same disk (because your snapshot just got fried too). Sure, you’ll probably get lucky – if your computer merely shut down uncleanly, your snapshot may still work. You might not even need to go use the snapshot. But this is not a backup, it’s gambling.