Strengths: Fairly nicely cushioned for the price. Pretty stable. Not too heavy (especially if like me your last shoes were New Balance) and cool in summer.
Weaknesses: Gave me blisters at first, but soon settled down. Tongue can slip down.
Overall: I got these from the Adidas Store, using their "mi adidas" service. The great advantage of this was that I got shoes specially fitted to my feet, which are wide and different sizes. Adidas can cater for this, so that's a plus.
When it came to running in them, I got blisters at first, but that soon settled down. Also, the tongue seemed to slip down under the laces. But I found them lightweight and comfortable, and got a marathon PB in these - very satisfied.
[Update 23/05/06] Come in various width fittings. Lots of support. Ethically sound (as with all New Balance shoes but unlike lots of other manufacturers). Cheap, for the level of stability you get.
Weaknesses: Can be a bit too roomy - I had to wear two pairs of socks
[Update 23/05/06] Fairly heavy and bulky - can feel like you're wearing clown shoes! Maybe too roomy in the forefoot (I had to wear two pairs of socks).
Overall: I had a fantastic London Marathon in these - and they were the only shoes I could find that didn't rub my wide feet!
[Update 23/05/06] These are reliable, solid shoes. Trouble is, they feel solid too!
I have always worn Asics - graduated from the 2110 to the Kayano for my first marathon. The 2110 was good but the Kayanos were something else - so snug and comfortable, running in them was pure pleasure.
I moved on to the NB857 because the latest Kayanos were too narrow - the great advantage of the 857s is that they come in various widths.
I wore the 857 for this year's London Marathon and had a great race. They offer lots of support and feel sturdy. But you feel the bulk when doing faster runs in training, or on uneven surfaces. Overall I'd recommend them though.