I have this lens and a 50mm 1.8. I use these together for portraits. Not being able to afford several L primes for ultimate sharpness at 600-1000 pounds each, this lens is the perfect alternative. It's lightweight (compared to the 2.8), and I don't need any faster as most of my work is done using strobes.
It focuses well, even below normal ambient tungsten room light levels, and feels great to use, with all the switches and rotators having a high quality feel.
Bottom line is that everyone who sees the images at 100% zoom on the computer always says how amazed they are that a lens can capture so much detail.
If you're looking for your first decent lens, and this focal length suits your intended use, and you've got 400 pounds, buy this lens. It holds it's price very well, so if you outgrow it, you can always sell it for minimal loss.