- Use it normally
- Use it excessively
- Use it casually
Did any of those operations cause it to:
- Make funny noises
- Drain battery more than normal
- Alert you to dead pixels
- Crash
- Become extremely hot
- Make you regret buying it
If yes, return it. if not, who give a *******? Seriously, I used to have extreme buyer's remorse with large (and small) products. "The grass is always greener... or cheaper...or newer... or a neat new color etc etc". Just use it and if you like it, keep it. if you don't like it or couldn't afford it, get rid of it. My 2006 MBP was the best purchase of my life, only just recently being replaced by the late 2013 15" 2.6 dGPU to keep up with editing 4k. The MBP is simply the best purchase you will ever make in your life (unless you're upgrading because a "newer better" model came out and you absolutely have to have the latest and greatest.
If you aren't comfortable with something, you'll resist it and look for excuses until you can satisfy your subconscious guilt for buying it in the first place. Eventually, if your subconscious doesn't get it's way, you'll end up resenting your laptop, yourself, and anyone and anything that assisted you in the decision and/or "prevented" you (read: failed to support you) in undoing the original decision. DON'T DO THAT. You have 14 days to make an educated, informed decision for yourself. USE that time effectively and make your final decision with no regrets. In the end, it's just money versus your happiness.
TL;DR Try it out yourself and see if you like it or not. If you yourself see something wrong with it or want to bring it back, return it and be happy.
Also, welcome to the Apple Family!

----------
I know there was a bunch of hubbub about the rMBP displays (LG vs Samsung) for example
Also, this: If there is substantial claim to any inherently poor features of a device, the company will either issue a replacement, fix the problem, or there will be a class-action lawsuit.
I have been given free replacements of the old-style 85W AC adapter for my MBP 4 times due to defective wiring causing shorts and fires (yes, it was VERY exciting). The last one they gave me was the newest model adapter that looks like a toothbrush versus the old ones that looked like... like... I don't know, a mini iPod connector cable with magnets. Anyway, rather than getting sued, they just replaced the faulty part, no matter how many times it went faulty.
So rest assured, no one is inherently out to screw you. And if they are, there's always litigation to exact due justice...