I have had my new macro lens for a while now, put it through it's paces and my old lens has gone to a new home. Sounds like it is time to do a round up of my thoughts on the new lens and how it compares to the old.
I adore the L version of the macro lens. The focus is much faster, it feels better balanced to me and the IS makes it much easier to handhold at lower shutter speeds.
I haven't really seen a big difference in image quality. I think the bokeh might be a little smoother but it was so smooth from the non-L that it is a really small change. For me there is no question it was worth the upgrade considering this is possibly my most used lens, and I use it even more now that I have the L version.
As for the auto-focus the L lens still hunts a LITTLE bit in certain situations but it is light years better than the non-L version. On the L you have three options, 0.3-0.5m, 0.5-infinity and full, for limiting your focus range. I love having the option to just keep it in the shorter distances, great for macro shots. There is no similar option on the non-L version only the 0.31-infinity (which is the same as full) and 0.48-infinity which is similar to the 0.5 to infinity. This little improvement has been huge for me.
It is at least as sharp as the non-L, maybe even a little sharper.
The IS is really useful as well. I couldn't really hand-hold at 1/100 with the old version and get tack sharp images 100% of the time, I can with the IS if the subject is still.
Overall I am 100% happy that I upgraded.
And because I hate to post without a photo, one of my newest favorites: