Depends on how you want to justify it to the wife. 

I was straight up honest with mine and told her I've always wanted a remote controlled something so she obliged.

My brother and I are STO.  Can we scout that by foot?  Sure, you bet.  Do I already know where most of the bad spots in the field are?  Sure you bet.  Is it fun to fly the drone over and in 10 minutes check on things?  Sure you bet.  We still scout by foot for insect pressure etc. so don't expect it to replace boots on the ground.

We did fix some more tile this fall on a 1/4 we run.  That field has terrible access with the access road being privately maintained 3/4 mile and then access is only in one corner of the field.  So basically to get to the back of the quarter is a little over a mile by foot (kitty corner across a quarter).  We knew it was wet but scouting by aerial give a REAL quick indication where the tile is plugged/not working.  When the contractor came out to fix sure enough it was broke about 10 feet from the intake. From the looks of it, it has been that way for quite some time.  Crop was always stunted but always dry come harvest.  Easy find and easy fix. 

Justification?  The corn around the "wet spot" was making 260 this year (highly abnormal).  Around the broken tile was 45.  Net 215 x $3.50 is $750/acre.  Wet spot was just north of an acre.  Like I said, I still justify it as a toy but it does have some use in ag.  And yes, I know, we aren't supposed to make "commercial" decisions with our "toys" but lets be honest, it's pretty hard to miss a 1+ acre lake from a plugged/broken tile line so I am not going to ignore it.

I liken it to a four-wheeler or skidloader.  Could we farm without one?  Absolutely.  Would I go back to not having one?  No.

FWIW, I have one of the VERY early x8 from 3dRobotics.  This was back when you could buy an almost ready to fly "kit" (partially assembled).  It's showing it's age now.  My brother in law flies a DJI and it is SOOOOOO much easier to handle than mine.  Down side?  He put his on the ground once and only once. It's pretty expensive to repair. I've put mine down many times but it's easy to repair.  I know there has been mega strides from all the manufacturers in the last 3 years on user interface and build quality.  I only expect that to get more refined as time goes on.

So you ask for a con?  They are somewhat expensive to get into and they do cost money to run.  Especially if you put them on the ground.  I have found it's not a matter if, but when you put them down.  In my case it was with the poor batteries that were supply by 3dr.  Once I started flying with better battery packs the reliability went way up.

Suggestion is if you are seriously in the market, find someone with the models you are looking at and have them over for a fly day.

Good luck!