ASM makes good skimmers. Most people who bash them usually have something more expensive and dislike the fact that ASM skimmers are almost as good for less money.
My opinion is ASM is as good as any conventionally designed skimmer. They really dont utilize many of the newer methods such as bubble plates, directional water flow to create water flow in cyclone like form, Air flow is good. I say they are solid B rated skimmers.
I had one. they are ok. In order to get them upto par you need to mod them. IMO you can go with the Octopus skimmers for the same price and they already come with all the mods you would do to the ASM. ASM is also out of business so replacement parts will be hard to get.