I would agree with others that the Lansky is pretty good, not perfect. It can be tiresome to use, esp on large knives. Personally I find it works best on smaller baldes, e.g. my 4" Moras, but less well on larger/thicker knifes- it can handle my Glock field knife, which has a thickness of about 0.2" and 6" long cutting edge, I think, but I am not sure how well it would handle on thicker, longer blades.
Although it is slower than say large benchstones or a belt sander, I did manage to significantly reprofile the edge of my Glock, using the extra coarse stone. However, the EC is now quite curved compared to the other hones- which can present problems in terms of keeping constant angle.
It can be irritating to use at times, but I do manage quite easily to get a shaving edge on my knives, micro-bevelling with the F(600) and UF(1000) hones- however, it has took me some time to learn how to use it proficiently (you could say the same thing about anything really, so that's not really a criticism). When I first recieved it I was very disappointed with it, and found it very hard to use, but over time came to quite enjoy using it.
The point about marking the edge is very important- when I first used the system I was just grinding the edge, which frustrated me, as I didn't understand at all about sharpening angles or anything.
Overall, I would say that the lanksy will get a shaving edge easily, once you have got the knack of it. It's not perfect, but once you've got the knack of it you can get really quite sharp edges. If you do get it, I would recommend the deluxe version- it has both the EC(70 grit) and UF(1000 grit) hones, which are both pretty necessary IMO.
BTW, I am looking to get a new sharpening system, and am wondering what people think of the Razor Edge System angle guides/kits? I knew someone who used them and who said very good things about them, but haven't seen anything at all regarding them on the forums. Would an Edge Pro Apex/Pro be a better bet?