Decent quality, amazing value as a combo.
First things first. If you were to buy them separately, for even around 15-20 pounds per unit, all of them will be sub-par compared to some of the more popular brands in that price-bracket. However, if you want to put together a cheap pc build, this is an amazing set of peripherals devices, that you can use with confidence until you upgrade to something more precise.
The best one is the mouse mat/pad. If you look at the pictures, and you think for yourself the mat is of the smaller variety, and it's scaled just to look more impressive compared to the keyboard for example, you are wrong. This mat is huge and it's very well executed. Had to burn with a lighter a small part of the edge, since extra feathering from the stitching was left, but that's to be expected with some units (you might not have to deal with this).
The mice is decent, and though the shape of it might give you the impression it's a grip type of mice, it's not, you will have to palm rest on it in order to be comfortable using it. Since my last one was a gripper, I might not be able to say for certain how well this one performs. One thing that might make not use it is the fact that it appears to be lagging (at least compared to more expensive brand mice), so you either get used to it (as I did in the past) or it's too annoying for you. The clicking is nice and soft(ish), doesn't put a huge strain on your fingers and wrist, as my Razer does. So overall a good performing mouse that should keep you going until you upgrade.
Keyboard. Haven't had a chance to test it thoroughly. It does light up, it has different colours and intensity levels, it's nice to write on and as long as you give it a good press, you shouldn't miss any keys. I've heard someone say that once you power it on it goes to its default settings in terms of light colour and intensity, which makes sense. As long as there is no software/driver on your side, this keyboard won't do anything but start from scratch every time. I mean for the money you couldn't expect internal processing power for the keyboard. Also there are some holes underneath, presumably to help out with spillage.
Headset - has to be plugged in via usb to light up. The sound is mediocre towards medium (depending on who you ask). The bass is heavy, the mids are lacking and the highs are somehow swallowed by the lows. At max volume you ca get a decent head massage since the vibrations and airblows are so strong. You could use them with confidence, but if you ever listened to well known brands, like Sennheiser and Skullcandy.(amongst many others, like I have) this will immediately sound bad. If you've always used cheap headphones (though you should really stop doing that) these will sound more than amazing, due to the output volume and consistency. And yes, consistency not fidelity!
So yes, this pack is more than decent for it's price, but pretty much worthless when sold separately.