I've put my recently purchased 95 C280 on the the Alldata system. I couldn't find any repair or maintenance manuals for this model car, so I was desparate to find something that could lift the cloud of ignorance about doing some of my own maintenance and minor repairs. The combination of this forum and Alldata has done a pretty good job of this. Since I judge all repair books against the standard How to Repair Your VW - A Repair Book for the Complete Idiot or something like that, from the 1960's, I'll tell you that Alldata is not in this league. Having said that, it's still pretty good.
It's geared to people with more knowledge and experience than I have but no more than a Chilton's book. It will give you a good feel for what you need to do for any given job and an idea of how difficult it is so even if you end up taking it to the repair shop you have some idea as to what's involved and can make a more informed decision.
It's worthwhile to use their demo which is for a '95 Toyota Corolla I believe and just examine what kinds of features it offers.
I was pleased enough with it to also put my 94 Ranger on the system.
I guess I feel that $25 per year amounts to about 15 - 30 minutes of repair costs and is bound to be at least that useful. Bob H