Holy shit, Corsair Neutron; that's a name I haven't seen in a while lol
Honestly though, I believe you'll be having more of a headache with the GPU, RAM and maybe the PSU. It's using a superclocked 670; which is around the same area as the GTX 960. The 960 isn't future proof for games at 1080p and will struggle running modern titles. Sure, something like CS:GO, Rocket League and Overwatch won't be too hard to run, but if you're trying to get Battlefield 1 or Fallout 4, you won't be running at high or ultra with 60 or more FPS and I would even argue the case that you would struggle on medium settings for some games. PSU is really dated, if it's the same model I'm thinking, that's running back either 2011 or 2012. I don't know how long your friend has had this build, but that's something I would be cautioned with. RAM is absolutely pitiful, 4GB in a system like this? You'll have to add in another 4GB to bump it up to 8 GB RAM minimal.
The CPU is fine, even if it's what, 4-ish years old now? Performance wise, I may be able to get off with claiming it would be around the same performance as a modern i5, which isn't bad by any means.
The case is definitely unique, but also has a few draw backs. First and foremost, it's too damn big for what's inside it. This case is like the Corsair 750D, in that it has a lot of room meant for watercooling; however, the case your friend has looks bigger than the 750D. It's great for being able to mount fans, but there is such a thing as too many fans; be that in the form of too much negative or too much positive air pressure. Another thing is the case is a vent in general, with no type of filter or magnetic filter in front of the vent holes. This allows pet hair and dust to build up inside your PC quicker, which can cause overheating and just make the inside of your PC look like shit. Is it the worse case in the world? Not even close, but with what's coming with the build, I think the case is too over the top.
With all of that said, ask if he will sell you parts. You could easily nab the CPU, Motherboard, SSD, HDD and maybe the RAM -- but then you have to buy another RAM stick, and lock yourself into 1600 MHz only -- if you buy the parts, you could come back with a budget to fill out the rest. You could also just use the $700 budget or a different amount if you have one for building your own PC.