Oh, SSDs are great! They are much faster than spinning drives in general, completely remove the seek-time delay in specific, and are far more resilient to kinetic damage (bumps, drops, etc.).
What I've kinda gotten sick of, however, is the "Cult of the SSD" here on MacRumors. Yes, an SSD will vastly improve long-term storage performance. Activities like bootup and application loading will improve as a result. But no, it won't make everything run faster, nor will it fix bugs in your software, nor increase the resolution of your monitor, nor cure hair loss nor remove unsightly acne from your skin.
People seem to think of an SSD as some sort of true Panacea, that you can drop this one device into a machine with a crappy CPU, a crappy GPU, and a minuscule amount of RAM, and suddenly it will perform as if it were a high-end machine. An SSD can only improve on what an HD does, no more and no less.
While a SSD won't make your CPU or GPU faster, it can greatly enhance the performance of a computer.
CPU's are generally very fast and efficient already. And essentially where SSD's provide the greatest benefit is getting data to the CPU faster.
Much of the time we spend waiting on a "slow feeling" computer, is actually due to the CPU waiting for the information it needs to arrive. Once the information is in the CPU, it is processed very quickly.
In my case, I have approximately 15+ drives attached to my primary Mac. Amounting to multiple terabytes of storage. Most of which is nearly full.
In the mix, I have 2 SSD drives. One has OS X and OS X programs loaded on it. The other has Windows 10 and Windows programs loaded on it.
Frequently used data like my email programs and messages are also on the SSD.
Anything that is temporary is always stored on spinning drives. Anything that is rarely needed is stored on spinning drives.
Large project files are also stored on spinning drives. My internet downloads go to spinning drives.
My iTunes library (6 terabytes) streams to my AppleTV's from a spinning drive on a USB 3 port.
Pretty much everything goes to spinning drives, except the operating system, programs, and data that doesn't change constantly.
Using this arrangement, the "feel" of the computer's perceived performance went from slow to instant. My daily tasks are now responsive and instant instead of waiting on beach balls.
It's a balance. The SSD doesn't make the CPU faster. But the SSD does get the information to the CPU faster. Which means the computer feels faster because you spend less time waiting for the CPU to begin the process.
I was reminded how significant this is the other day when a friend brought me their newer MacBook Pro so I could help them with something. By specs, their MacBook Pro should have made my computer look like snail.
But, they had the spinning drive in there. I didn't believe them when they complained about how slow the computer was. I'm like yeah right, top CPU good specs, you're crazy.
But even freshly reinstalling OS X on a formatted hard drive made no difference.
Their computer felt like a snail. Everything was lagging. Everything I clicked on took a long time to open and display information. Even waiting for "about this Mac" to open felt like forever.
The computer can only process information as fast as its slowest component can provide it with the information.
But yes, in things like video playback, speed is less of an issue. It doesn't take much to display a video file at 30 to 60 frames per second. The information is already being delivered slow enough for our brains to visually process it. So a spinning drive is more than adequate. Our eyes and brain speed are the limiting factor when it comes to video playback. If a computer played the video as fast as possible, we would not be able to understand the video. Our brains are too slow.
