I have the 50mm 1.8 and used it quite often, but I found it to be slow and it would get stuck sometimes. It was less then a year old. I bought the 50mm 1.4 and now it is permanently on my camera. I love the sharpness it has given me. I can definitely see the difference betwen the 1.8 and 1.4. I highly recommend it.
Mama Monkey-
I completely understand where you coming from about eyes in photos. If they are not crystal clear...I'd toss it too!!
Here is a trick I learned reading the Digital Photography Book by Scott Kelby and it has helped big time.
Shoot at your lens' sharpest aperture or "sweet spot" Every lens has one. Most lenses that is about 2 full stops smaller then wide open.(so the f-stop number you use will go higher by 2 stops.) ex, if you have a f/2.8 lens,the sharpest aperture for that lens would be f/5.6 and f/8(two full stops down from f/2.8). Now you won't always be able to shot at that aperture, but when the situation lets you...go for it! Hope this is helpful...Good luck!