My previous pair of running shoes were also Asics, but they only cost about £35. As soon as I started using them for running, however, instead of just the occaisional class at the gym, my feet were torn to shreds. It was clear I needed to get something that suited my feet specifically. I've got a moderatly high instep and my ankles roll in when I run so, after getting some advice, I chose the Kayano 17.
I haven't been disappointed. Blisters are a thing of the past for me and my feet never ache after I've been running. I know that the real benefit of these shoes are the long term ones; in that theyh will help to prevent damage to my knees etc by supporting my feet correctly.
The gel heel is a fantastic feature and moulds to your feet perfectly. It's a bit like having memory foam for your feet! Overall, I'm delighted with them and I'll be running in them until they fall apart. Then I'll buy another pair!