Pros: none

Cons: This wireless mouse and most of Logitechs wireless mice use the 2.4GHZ frequency to operate. If you have a wifi network or other electronic devices that use the 2.4GHZ frequency you will experience random sever lag between both the mouse and keyboard due to interference between the devices over the 2.4GHZ frequency. There is no way to change the frequency used by this device.

Other Thoughts: If your wifi network uses 2.4GHZ I would not recommend this mouse/keyboard combination be used. Instead grab the MS combo which works without issue.

Pros: Very good Price & they work very well.

Cons: No Cons

Pros: Econimical
Wireless

Cons: Mouse locks up and freezes at random.

Other Thoughts: I thought my issue was with 2.4GHz frequency interference, except it locks up instead of lagging badly. I replaced the battery the first time and then it froze a couple of days later.

I tried new drivers, reinstall drivers, install Logitech software, different USB ports, even usb 3 ports, etc. Nothing seemed to work.

I then pull the battery as they were generic batteries and thought it may have went dead. But the battery slipped out of my hand and fell back in and it started working again.

It now locks up every day and only works until it goes to sleep and won't wake up until I pull the battery and put it back it.

Too much hassle, getting a new one. Probably another Logitech as this is the first one in years (I've been a customer for decades (80s) and this is the first product by them that has ever had any issues)

Hopefully just a freak of nature as Logitech has always been gr

Pros: Sturdy build quality. This is a good looking and good feeling keyboard and mouse combo. Not too heavy, it'll let you sit in a chair and use the PC from across the room. Great if you use a TV as your monitor, like I do.

Got this for sale for $15, so that's one consolation.

Cons: Horrendous and well documented lag issues. Check the Logitech forums and you'll see numerous users asking if their keyboard needs to be RMA'd. Nope. That's just how it behaves. It seems that if the keyboard is too close to the receiver, the system will frequently queue up keystrokes and then spit them out all at one time. Needless to say, this is not the keyboard to use if you plan on doing any document writing and gaming.

It also gobbles up batteries like toddlers gobble up boogers.

Other Thoughts: If you do purchase one, attempt to move as far as possible from the receiver. This may minimize the lag issues. Otherwise, I recommend the Logitech K400 Wireless Touch Keyboard, which is small but fantastic.

Pros: Decent appearance, build quality is on par with other Logitech products. Nice keys and mouse is a decent size unlike some of the other combos.

Cons: This combo works on the 2.4ghz band and it has constant interference with other electronics such as phones and wi-fi signals. I have purchased 6+ of this combo for the office only to find out they all have interference issues and constantly lag and stutter. I am 2 feet from the usb reciever and the keyboard lags horribly or sometimes will not pick up keystrokes at all. The mouse is the same, causing it to jump all over the screen, which is terrible for using applications like Photoshop and Illustrator.

Other Thoughts: I am a big fan of Logitech products and have used them for years, but in this case I would move on to the next product. A quick google search will tell you that numerous people have the same issue with this combo and Logitech has never addressed it.

Pros: Decent keyboard for the price & with unifying tech you can attach more Logitech devices to a single usb adapter. They seem to hold out to punishment well also. I have on occasion dropped these ( I have more than two) from about a 4 foot high level & have yet to break one. I'm surrounded by comp's in a tight space & every once in awhile I snag one & it hit's the floor. Guess I need to build a bigger room so this does not happen as much.

Cons: Nada

Other Thoughts: I do like the keyboard but the mouse that comes with this unit is rather large (I am use to smaller mice) and does not track as well as the smaller Logitech mice.

Pros: Plug in the dongle turn on the KB and Mouse, ready to go. Bought for my GF she likes it, that's all I needed.

Cons: none so far

Other Thoughts: It'sa a great wireless combo, fantastic when it's on sale!

Pros: Nothing outstanding

Cons: One small issue and one larger one.
As a personal preference, the keys at the bottom of the keyboard (the Ctrl keys, chiefly) are too short, and when depressed go down below the level of the keyboard itself. It makes it a little awkward to make proper contact with them, but that is likely as much a personal typing style problem than anything else.

The big problem is that there are lag issues that I haven't been able to resolve. Occasionally, the mouse will stop responding for 1-5 seconds at a time. Less often, the keyboard suffers the same problem.
I've tried other keyboard/mouse combos with no problem, and I've tried installing the Logitech drivers with no solution.
If I can't get a resolution soon, I'll have to try to RMA the combo and switch it for a Microsoft set.

Pros: Its by Logitech. Works as advertised.

Cons: As a long time Logitech fan I've been disappointed with this new version of the 520 series. I have had an S520 combo for several years and it has been excellent. This new version MK520 with the low profile keys and short palm rest just does NOT fit my hands, fingers or touch. The old series had two elevation tabs for two different heights. The MK520 has only one and it is too high for my taste and sitting flat is uncomfortable. I had to put spacers under the top edge to make it more useable.

Pros: Unifying wireless, accurate tracking with mouse.

Cons: Definitely not one of Logitech's finer products. I purchased two, and when the sets were 12 feet away they interfered with each other. Suddenly one mouse would stop working, or a keyboard would be very unresponsive. I have in the past successfully connected two Unifying receivers to the same machine each with their own keyboard / mouse and it worked just fine. Not with these, though.

The keyboard is flexible, and made of that low grade of plastic that absorbs finger prints and becomes shiny after an hour of use.

Other Thoughts: For as much as I can complain, I am still using them and after swapping out one of the Unifying receivers for an older one I had, they are working. It's just that compared to most Logitech stuff, especially at the price, it seems cheap.