i've got the dl (not apo) version and am quite happy with it. have noticed very little problem with purple fringing, etc. but my previous camera was not a dslr so i may be setting the bar kinda low.a lot of people do recommend the apo version.
mine is an older one and the macro setting only works at 300mm. the newer ones (i'm pretty sure) allow you to use macro at a range of focal lengths (i think 180-300). i got the lens largely for its macro function and if i had it to do again would definitely spend more to get that flexibility. (i got it used for US$104).
good luck, eric