I used Motorcheck.ie which is pretty much the same thing. I was helping a mate buy a used car and wanted to verify a couple of things, which the report did. If you PM me your email address I will send the report to you, and you can see for yourself what it entails. By the way it cost €30 if I remember correctly.
I used them when I bought a car. It's an ok price for an extra bit of reassurance but it's not great, however if you intend to do a mechanical check, I would highly recommend the AA. I got the AA to inspect 2 cars and they were cheaper than the cartell.ie and they were excellent.
Regarding buying from a garage, don't rely on that too much, a while ago I was going to buy a car from a reputable Dublin dealer but I got the car inspected by the AA and it turned out that the car had been in a high speed accident with all the panels replaced (see here http://www.askaboutmoney.com/showthread.php?t=35515). The AA guy gave me lots of detail and even explained how very sophiscated techniques for hiding the damage were used. I'm sure this is an isolated example but I'll always get the inspection done before buying again, private or dealer.
I used Motorcheck.ie which is pretty much the same thing. I was helping a mate buy a used car and wanted to verify a couple of things, which the report did. If you PM me your email address I will send the report to you, and you can see for yourself what it entails. By the way it cost €30 if I remember correctly.