What would you have done

Very good question and happens quite often.  My only shot doing this turned out well.  It wasn't purely straight on.  He turned his neck and shoulders slightly to his right.  My arrow entered high in front of the left shoulder.  Passed through top of heart and some lung, exiting low near last rib.  He barely made it 50 yards.  This was nearly my last day of vacation.  That is no excuse for taking a marginal shot.  But at 10 yards I could pick the exact spot I wanted.
 
Straight on, you're looking at a single lunger or heart shot.  Not a lot of room for error.  It's a personal judgement call.  I say take what the buck gives you within your own abilities.  Also need to consider the weather factors.  If dry, cold on private property, I'd take a 1 lunger and let him lay down over night.  Might not get a lot of tracking blood with only entrance hole in fatty brisket.  Of course you don't often think of those things in the moment.  But you can plan ahead while sitting on stand up to that moment.
 
I would prefer a straight-on to quartering-to if really close.  Hate those shots where you get to choose between shoulder blade and liver, with a slight window for lung.  If far away (>25 yards in my book).  I'd pass on both.

 
As long as you shoot 3 inch circles out to 30 yards or so and the Deer is still and not gonna jump the shot by seeing you its likely doable..
     That's a tough shot for anybody with only a narrow  target and excellent chance of a wounded deer running around. Gotta remember your shooting on a down angle  with a close deer- it may be hard to get into the cavity even hitting where you aim..
I have generally passed it .The one time I tried it chose to aim high where the neck kinda meets the body. Bled out real quick and didnt go very far at all- watched it go down.
 NEVER feel bad bout passing any shot that you aren't comfortable with- its the best choice. Second guessing always happens but don't let it get in the way of a wise choice.
  Also remember that 'straight on' with a Deer that's actually passing by is likely a bit of a quartering to  shot=the worst lousiest bow shot going.
You did the right thing.

IMO that's a poor shot choice with a bow.  It can be done and it can be fatal, but the margin of error is too small for me to ever condone that shot. 
 
 

He would almost have to be looking up, and i think you DEFINITELY did the right thing passing on the shot.
 
I took a shot almost straight down this year, and it went a half mile, with the wildest most intense 6 hours of tracking you could imagine(I also believe he was jumped by a 3rd party, nevertheless).  Single lung is a BlTCH.  I also took a shot 3 years ago, straight down, and sliced the heart in half, and he took 5 steps and rolled over and died.  Difference was one was quartering to, the other was straight under, spit on him shot.  That "looking at you" shot is tough to pull off with a rifle, much less with a bow, elevated, steep, 10 yards...... 
 
If I were to get the optimum shot, it would be quartering slightly away, 15 yards.  But when does that happen?  Once every 5 seasons?  Always think about the arrow path through the deer, bones, organs, shoulders, etc.
 
One thing I do in practice, I shoot off my roof with short shots, and also try to practice holding at full draw for 30 seconds or more before releasing.  These things help with confidence at pulling off those shots.  Practice throughout season too, even it is just a few shots every couple of evenings.
 
You did the right thing dude!  Congratulations on making an ethical choice, I know hunters much older then you that would have made the wrong one!  You will be rewarded in the long run, it makes for good mojo.....

I'm with the others who said it was a good decision to pass for the reasons already posted.  Better to question yourself and let him go than to make a mistake and just wound him.  
Still have plenty of season left to put a tag on one.  At least you have seen a legal deer.  Still haven't seen a legal buck while on stand this year and I got blanked on deer on Fri. and Sat. evenings.
Still better than sitting on the couch!

I can't say you should have released the arrow I wasn't looking through your peep. Sounds like you made the right choice to me. To many guys would take even more impossible shots and send them, I have found several dead ( waisted ) deer because of bad judgment calls. Take care E

 I give Eman credit for a common sense decision also...not a expert here by any means  but he did the right thing I think.  Maybe I'm to picky at times & never take the shot but I usually feel better at the end of the day with my decision.  I took a shot at a button buck last Friday night which I hurried the shot and missed but looking back at it I'm glad I did. I didn't put tags on anything this season but that's OK ,I had a great season.

Good Idea Ed, I would try to stay all day! Most gun hunters are only going to sit so low before they get antsy and start the push. And that my friend will pay off for you just have patience and be ready. More than likely the deer will coming in HOT, and have the grunt in hand. Good Luck Dave

i think you did the right thing Ed. here is a link someone posted once before
http://www.bowsite.com/bowsite/features/articles/deer/deergeometry/

I guess it all depends on what feels worse, knowing you took a pass on a big one, or knowing he's out there some where dead and rotting.
I've never had the misfortune of a non-recovery, but there's only been one time I second guessed taking a pass and that feeling only lasted a few hours. My first year of hunting on my own(rifle) I had a huge buck cross behind me and had an excellent 40 yd broadside shot. Gun raised, already thinking of the trip to the taxidermist with my first buck, I saw the yellow of a school bus passing trough the trees behind him(as he was between me and the highway). That was that, I just couldn't bring myself to shoot. I waited for him to move along the trail and give me a good shot but he never did. At the end of the day, I told my dad what happened. I thought he'd be disappointed, but he wasn't. I think he was more proud of me passing on a dangerous shot than if I would have downed that monster. He even went as far as to repeat the story to all his friends after we got home. Ever since then, I too take pride in passing an iffy/unsafe shot. I believe it's one of the main characteristics of a true hunter/sportsman.  
 
On the flip side, I have a super lucky buddy who seems to rattle/grunt in a nice buck every couple years. He shoots all of them. He's recovered about half. Don't get me wrong he's a good dude, and would never intentionally take a bad shot or wound a deer. However, buck fever does strange things to one's judgement. It can make a bad shot look good  and post-shot wait time seem like days. He has gotten much better and the his last three bucks have been recovered(not the case for the first three). Hopefully, he's gotten over the effects of buck fever. 
 
For what it's worth, I'm proud of you for taking a pass. He'll be bigger next year anyway.