135 is the std for portraits... so I would say it is a great lens for overall utility...the shorter length for everyday shots and the zoom for close up sports, plus it has an extra f stop withe the IS and you can do some real cool effects by zooming while shooting...so IMHO the 70-200 f2.8 may be the best lens overall...
Thomas Edison said,
"I have not failed. I've just found 10,000 ways that won't work."
Think about that the next time you want to give up after 2 or 3 attempts...