I'm extremely happy that your phone didn't receive much damage, I had a pretty terrible experience once.
I used to own a Sony Xperia S, dropped it several times and each time the sides or something got chipped. In total I dropped it thrice, the last time was on February 2013, I was playing badminton when I dropped my phone.
Initially the phone worked completely fine, no scratches or anything but as soon as I got home, it was completely dead and never got fixed. A good $400 wasted sadly.
I've since realized that Sony products aren't the most durable, I even own a laptop made by Sony and though I've never dropped it it has cracks on the back hinges.
Nokia has a history of durable phones but that does not in any way mean that the new Lumia range is just as durable, my Lumia 520 got quite a lot of scruffs near the sides and two of my friends broke their Lumia 720 and 920.
My honest advice to you would be, get a cover or you'll provably regret it a few drops later.