Hipster-
Basically - it's just like Vladimir said..
Firstly - come in IFR proficient.. it would help to download the garmin 430 sim and learn to go direct to an airport with it and how to load approaches with it..
Go over the manuvers in the book.. Chair fly them..
But.. to answer your questions directly..
Whats the quality of training- On par with every other flight school in the country.. Alot of that will vary by the instructor you get..
How are the aircraft.- They are great and suberbly maintained..
Did you go over the 10 hours. -
If you buy a 10 hour program, depending on where you do your training you will get "up to 10" hours.. ATP is not a time building program, if you are ready to go in 5 hours, your going.. Which is probably why scottnflying didn't get all 10, he simply didn't need it to pass the ride..Most students go the full amount..You WON'T go over, unless your paying for it..

Going over 10 hours means you were not ready or you busted your ride..
Whats the study material like. - Come into the program with the first 16 pages of the Piper Seminole Supplement well read and understood.. If you can flip to the last pages in the book and answer the 44 questions verbatim, you will be fine for your oral.. You need to know all the vspeeds, etc.. Know your airplane.. Your already IFR rated, so there will be little "rehashing" info you should already know.. You will be tested on the "new" info mostly.. The twin stuff.. You must know the items dealing with a twin.. Vmc, critical engine, Pfactor, torque, accelerated and spiraling slipstreams.. You also need to be familiar with what is Vmc and what contributes to Vmc such as things like standard day conditions, most unfavorable weight, aft cg, critical engine windmilling, flaps and gear in the up position, up to 5 degrees of bank into the op engine and max power on the operating engine.
Whats the checkride like. - Depends on where you do the training and who your examiner is.. Some are of course easier than others.. I will say this, in most cases, if you can pass a checkride with one of the ATP examiners, you will be fine with other examiners - the examiners do not "work" for ATP... They are simply examiners for ATP because they have the PA44 on their ticket and can give ATP Rating checkrides, which is the bread and butter of ATP..