I have a Spring 2011-vintage Unibody MacBook Pro 15", 2.0 GHz Core i7. I had been researching SSD drives for some time, and the Samsung 840 Pro was always relatively Rather Expensive, but also consistently highly rated for speed, reliability and life expectancy. For those reasons, I decided to pay about $90 more for the Samsung, vs. what a 512G Crucial M4 was going for at the time.
The Samsung SSD comes in a little lightweight cardboard box the size of two stacked-up CD jewel boxes. If your shelves of "assorted computer stuff" are like mine, you could misplace the box waiting to put this thing in! Installation was very straightforward, no different from a traditional hard drive. The Macbook Pro and the Samsung drive both support full 6 Gigabit SATA link speed, and this was correctly shown in the System Report once I had OS X 10.8.x freshly installed.
You don't need benchmarks to measure how fast this drive is. From a cold, turned-completely-off start, my MacBook Pro boots all the way to the desktop in about 10-12 seconds. Applications launch on the first bounce of the icon. Even Thunderbird. Even iTunes with a >100G music library. INSTANT. It's mind-blowing.
Plus, my laptop runs a few degrees cooler, and has better battery life. Neither of these improvements are huge, but they are noticeable. Also, in a quiet bedroom late at night with no window fan or A/C running, I also notice... the lack of the subtle whirr of the old hard drive. As long as I don't load the CPU enough to bump up the fan speed, my laptop is now ABSOLUTELY SILENT.
In short, the Samsung 840 Pro is a small package of pure, concentrated awesome. If your particular laptop still LETS you do things like installing memory or a hard drive yourself (i.e. unlike Apple's newest Retina Display models, where everything is factory-soldered to the motherboard) then these two vital upgrades will take you and your (in my case) two-year-old laptop, and transport you both to computer Nirvana:
1) Upgrade the RAM. Memory is very cheap these days. If you have 4G RAM or less, bump it to 8G or more.
2) Replace your rotating platter hard drive with a solid-state. The Samsung 840 Pro Series is an EXCELLENT choice here, and I think is worth every bit of the 20% price premium you'll pay over a more mid-line brand with the same storage capacity.
That concludes the review proper. What follows are some general SSD observations and tips, plus some advice specifically for SSD's on Mac OS X.
SSD's are very reliable, but they do have a finite ability to write and re-write data in each memory cell of the drive. The Samsung has a 5-year warranty (and you DO make backups of your data, yes?) and really, the amount of data you'd have to throw at a solid-state drive to actually wear it out is so tremendous, no ordinary user will ever even come CLOSE to it. So drive wear should not be a practical or everyday concern. (A few months ago I dropped one of my old-style external hard drives a few feet onto a hardwood floor. THWACK... Dead. Makes the SSD advantage very clear.) Still, there are things you can and should do to avoid unnecessary wear on your SSD drive, and maximize its life.
* DON'T run performance benchmarks on your SSD. Drive benchmarking throws HUGE writes and reads at the drive to measure the performance. Let the computer mags and professional reviewers do this for you, don't cause YOUR drive needless wear just testing the speed.
* Enable TRIM support. This lets the drive manage re-written data more efficiently and properly refresh memory cells that become available as files are moved or deleted. (Mac OS X has had TRIM support since 10.6.8, but if your laptop didn't come with an SSD from the factory, you have to turn this feature on yourself, with a utility like TRIM Enabler or Chameleon SSD Optimizer.)
* Consider disabling "Hibernation". My laptop has 8G memory. This means that every time the lid closes and it goes to sleep, it writes ALL 8G OF RAM out to disk. Turn this feature off, you'll get less wear on your SSD, and the laptop will sleep and wake faster -- however, the one disadvantage is, if your battery goes completely dead, your system will lose its operating context, just like any computer when you yank the power. Command is "sudo pmset -a hibernatemode 0", and then you can remove the "sleepimage" file from /private/var/vm/ to reclaim the disk space. (PC laptops typically have settings for "sleep" vs. "hibernate" as well, but I didn't research specifics on those.)
* (OS X 10.8+ only) Disable local backup snapshots. Starting with Mountain Lion, OS X's Time Machine keeps regular backup snapshots locally, whenever the external backup drive is not available. These don't really gain you much, IMHO. If your laptop falls into the Grand Canyon or your internal drive croaks, those interim LOCAL backups won't be any use anyway. You can turn these "snapshots" off, save the extra thrashing of your drive, and Time Machine will still work exactly as before when you DO connect your external backup drive. Command: "sudo tmutil disablelocal".
* Disable the Sudden Motion Sensor. This automatically parks your hard drive heads to prevent a crash if your laptop falls off your desk. SSD's don't need this shock protection. (Of course, if you have a second, traditional, hard drive in your machine as well, your should leave this protection turned on.) Command to disable: "sudo pmset -a sms 0".
USUAL WARNINGS AND DISCLAIMERS
If you aren't already comfortable with working in Terminal and on the command line, or you don't know what "sudo" stands for, ask an expert to help. ("sudo" is God-level access to your machine's systems. Remember that sometimes God parts the Red Sea, but sometimes, God floods the entire planet and everything on it DIES. Be sure you know which one YOU are doing.) Google every command first, read a few articles for each one, and thoroughly understand what they do. Read the man pages for tmutil and pmset. I found ALL of the above information online pretty easily, but it did take some research. I am just putting all of the suggestions in one place to help you get started. (You may find additional suggestions and settings in your research that are helpful on YOUR system, but these are the ones that I decided to implement on my MacBook Pro after installing the Samsung drive, and they are working well for me.)
And do enjoy your Samsung 840 Pro. Every time you wake up your laptop, it's like going out to your garage to go grocery shopping, and remembering that, Oh, Right -- I own a Ferrari. COOL.