It's possible, but it's time consuming if you don't know what you're doing, and expensive since unless you have a laptop with Windows 8 Pro, you don't have downgrade rights and need a new license. So, even turning a blind eye to the fact that you can only get Windows 7 as an OEM version and the OEM EULA terms were altered to explicitly prohibit you buying a copy to load on a computer you personally own and use, you're looking at about $120 for just the copy of Windows 7. Even if you did have downgrade rights, you couldn't just download one of the Windows 7 ISOs off the Internet and use that. Brand name systems that shipped with Windows 8 tend to have the product key embedded into the UEFI, so there's not even the sticker on the outside of the case with a code you can enter in, creating an additional hurdle to clear before you even get started.
Once you have a copy of Windows 7, you need to track down the requisite drivers and know the proper order in which to install them. There can also be a few additional bumps to trying to install Windows 7 on a system with UEFI, which all new systems will have.
If at any point along the way I lost you, then you're not ready to install Windows on your own and attempting to do so will likely result with a non-working system.
Frankly, when I had to get a new computer I was a little apprehensive about Windows 8 and was really close to paying a little extra to get Windows 7 installed. I decided to roll the dice and am actually quite happy I did. I basically just ignore the start screen except for the weather app so I can check to see if I need a coat or umbrella. My core apps are all pinned to the taskbar, so it's rare I ever need to see, let alone interact, with the start screen and even when I do it's not THAT bad, just momentarily disorienting at worst. I haven't even bothered to check if there are any worthwhile apps in the store. The rest of Windows 8 is an excellent series of minor improvements and complete overhauls of some tools. I'm a huge fan of the new task manager which folds in a lot of the functionality of the old msconfig program along with some other nice improvements. Being able to natively pause/resume file transfers gets two big thumbs up from me as well. Not to mention the right click menu for the new start button which saves me all kinds of time by listing some of the most commonly used control panel functions and a few other useful things. Because Microsoft is trying to pitch Win 8 at tablets, they've put it on quite the diet, slimming the OS down considerably compared to Windows 7. One thing I might personally recommend, is making sure you know how to create a "local" account right from the beginning, unless you like some of the things that can be done if you tie your Windows account into Microsoft's online services.
There's a lot of people who haven't even used Windows 8 that have decided they hate it and there's something of an echo chamber around that whole sentiment. Plenty more people who have used it but can't be bothered to spend 5 minutes with Google to try and find an answer to the problem. You almost never have to see the start screen unless you want to and after that, it really is a very nice upgrade.
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