Welcome to AT mahjjima!
The good thing about this build is the i5 3570K forms a good foundation for this PC to be upgradeable on the GPU side for years to come. I would say this platform will last 3-4 years if you get a $30 after-market cooler and can overclock the CPU to 4.5-4.6Ghz. The CPU can easily accommodate a GTX980Ti level upgrade down the line.
Monitor new is
$160
Mouse new is about
$58
This level of videocard can likely be picked up used for $80-90, maybe even HD7950.
1TB mechanical drive is worth about $40-50.
8GB of DDR3 is $40-45.
That leaves us at $378.
Any decent PSU is at least $35. That puts us at $413, leaving just $87 to buy a CPU. It's going to be very hard to find a CPU as fast as the i5 3570K for $87.
So all in, it's a good deal, but there are some long-term sunk costs/compromises in this build. What I mean by that is it might make sense to spend $150-200 more on hardware and try to build a Skylake i5 rig with another GPU. But then again, it might make more sense to sell the 7870 and/or invest that $150-200 + ($100 for the OS) towards a faster GPU now or a future 16nm HBM2 GPU. More on that below:
PSU
1) You haven't listed the quality PSU in this build (brand, power rating, 12V rail combined output). For example, for
$35, it's possible to buy an XFX 750W which will last 10+ years.
GPU
2) The GPU is limited to 2GB of VRAM. Generally speaking this is becoming borderline. It would be possible for you to pick up an HD7950/7970/7970Ghz for $90-120 if you look hard enough. They have 3GB of VRAM and are much faster once overclocked. But this is not a deal breaker as you can always sell the 7870.
Mechanical HDD
3) 1TB HDD - without an SSD, most modern PCs feel slow. You should always have an SSD or an M.2 drive in a 2015 build and beyond.
Monitor
4) That monitor is a TN panel. Without doing an extensive research, it's possible to find 1080P IPS panels for $20-30 more, or on special sale it's possible to find an IPS monitor for less than $160:
ASUS VC239H Slim Bezel Black 23" 5ms (GTG) HDMI Widescreen LED Backlight LCD Monitor IPS , 80,000,000:1 Built-in Speakers =
$130
ASUS VS239H-P Black 23" 5ms (GTG) HDMI Widescreen LED Monitor 250 cd/m2 ASCR 50,000,000:1, IPS Panel =
$160
ASUS VN248H-P Slim Bezel Black 23.8" 5ms (GTG) HDMI Widescreen LED Backlight LCD Monitor IPS 80,000,000:1, Built-in Speakers =
$178
And these are new too, not used.
Memory
5) DDR3 memory. 8GB is sufficient for probably 99% of games but should you decide to upgrade in the future to 16GB, you are just sinking $ into outdated DDR3 tech that can't be reused in a future CPU platform upgrade. It might make sense to pay a little bit more and buy a system with DDR4 now.
Ok so instead of it costing $40, it'll cost about $60-63, but at least you can carry this over towards your next CPU upgrade. DDR4 2800 8GB
$63. And this isn't a sale price either. I bet there will be better deals on DDR4 closer to the holidays.
CPU
6) CPU - IVB is a good CPU but the motherboard lacks proper PCIe SSD support, proper M.2 SSD support and doesn't have USB 3.1. So while you save a little bit short term, in the long-term, with an Skylake i5 platform you have more possibilities to add
blazing fast PCIe SSDs or take advantage of hopefully future external 3.1 USB HDDs/flash drives.
OS
7) The other pro of the build you outlined is I assumed it has a legitimate Windows OS that can be upgraded to W10 for free until next June 2016. If you buy your own components, the cost of the OS would raise the budget
at least $100. So in that case, the build you outlined looks even better.
The counter to the above of course is that if you have to spend $150-200 extra on hardware + $100 on the OS, you could in theory just buy the system you outlined, sell the HD7870 for $80, add $150-300 and get a faster GPU like the R9 290/290X/390/970 or use the 7870 and get a new graphics card built on the new 16nm node with HBM2 memory by late 2016/early 2017. But again, just wanted you to know some pros and cons of your system.
To give you an idea of how well that PC will play games,
check out a bunch of game videos on an i5 750 @ 3.7Ghz + GTX760. That level of performance should be fairly close to a stock i5 3570K + HD7870.
The build in your sig is definitely going to provide a better gaming experience against a PS4. The good thing is the i5 3570K is a fast CPU, especially if you get a $30-40 cooler down the line and are able to overclock it. The only thing I would confirm is the power supply brand and power rating and also what motherboard comes with this build. Hopefully the PSU is at least 500W.
BTW, your type of subject area would probably be best suited towards General Hardware section, not Videocard and Graphics sub-forum since you are concerned with the overall experience/bang-for-the-buck of this system, not just the graphics component.