The Digidesign AIR (Advanced Instrument Research) Multi-Delay is a new plug-in that comes free when you buy or upgrade to Pro Tools 8. It isn't available in any other forms, so only Pro Tools 8 users can use it. If you have an earlier version of Pro Tools, I'd recommend doing the upgrade as it is worth it for plug-ins alone, let alone the great new interface and features. You don't need to do anything to installed the Multi-Delay plug-in once you've gone ahead and installed Pro Tools 8, as it installs the plug-ins during this process. The interface of the software is pretty in depth, as you've got five different 'tap' sections for different delays. For the main parameters it has knobs for delay, feedback, high and low cut, and mix level. For routing the five different delays, you've got knob for 'from' and 'to,' so you can set it exactly the way you want it to run. Each of the five sections has the same parameters for delay, level, and pan, as well as an on button. I don't think that they make a manual for this, and one isn't really necessary either way.
I'm currently running the Digidesign AIR Multi-Delay in Pro Tools 8 on a Mac Book Pro that has a 2.2 Ghz Intel Core 2 Duo processor and 4 GB of RAM. I run Pro Tools with a Digi 002R audio interface or a Digidesign Micro Box depending on where I'm working from. These AIR (Advanced Instrument Research) plug-ins that now come free with Pro Tools 8, are designed to take up a small amount of processing power. The Multi-Delay does have more going on with it than most of the other AIR plug-ins, but keep in mind it is also one that you generally won't be using as many instances of. As long as you have a system where you can currently run an earlier version of Pro Tools with some plug-ins without a problem, this definitely won't be an issue.
So far in the short time that I've been using the AIR Multi-Delay plug-in. since I just recently upgraded to Pro Tools 8, the AIR Multi-Delay has become one of my favorite free new additions to the Pro Tools suite. It actually has a very clean sound quality and offers up a lot of versatility. There is definitely a good amount that you can do with the plug-in, as the five different delay sections make the possibilities plentiful. No one should really be complaining about this plug-in since it does come free, so I won't at all. If you've got Pro Tools 8 I'd highly recommend at least trying out the AIR Multi-Delay plug-in, as it is free and there for the using. However, if you've got other delays that you paid for, chances are that this one won't be upending your regulars anytime soon...