I recently took the interview at Compass and found it as straight forward as advertised. Since there wasn't much of a gouge when I interviewed I thought I might be able to help with this post.
Some things I learned: they're going to have "electronic flight bags." They're not going to have the HUDs as previously advertised. There are rumors that the time required to flow through might be lowered.

The 727 sim was as advertised: basic airwork and a hold entry - no ILS (so much for all that practice).

The ATP written is also as advertised: the most obscure questions they could find. There were typos - I'm not sure, but I think they use a static question bank of only 75 questions.

To prep for the interview I practiced hand-flying ILSs on the line, read as many forums as I could, practiced the ATP written and called everyone I knew who interviewed there (I know three guys that were offered the job - two that accepted it). (BTW, that was one of the questions: how did you prepare for the interview?)

The HR interview was also as advertised, two retired northwest pilots and the HR consultant. All three were good people. There were no technical questions.

I now submit to you the following bank of questions I compiled to prep for the HR portion of the interview: (I found that answering these questions put me in the right mindset to take the interview)

Tell me about a time when you had a conflict in the cockpit, and how did you resolve it?

How would you handle a situation where the FO was not adhering to SOP and when you said something he ignored you?

Tell me about an emergency you've had.

Have you ever broken a regulation?

Have you deviated from company policy before?

What are some strengths that are not on your resume? Tell us something about yourself that is not on your resume.

Do you have any other hobbies or interests?

In your opinion, what is the best flying job?

Where else have you applied?

How do you see the rest of your career laid out?

What do you think makes a good airline?

Tell me what you like about the place you work now?

What do you not like about where you work?

Are there any parts of your job that you don't like?

Why do you want to work for us?

Tell us what you know about the E175.

Tell us about a time you've done something for a customer that you weren't thanked for?

When have you had a customer problem? How did you resolve it?

Have you ever been angry at an FO? Have you ever yelled at one?

Many of these questions were on the HR interview. Here are a few specific questions I remember:

Let's say you had a lazy FO and after boarding you suspect that he didn't preflight the aircraft (the aircraft just came in from a trip). When you ask him he confirms that he didn't do it. What would you do?

What is the emergency procedure for smoke in the cockpit? What would you do in a serious smoke situation? What would be the minimum runway length you would consider if you had a serious enough fire? (I said that with enough smoke even a highway starts to look great option)

What would you look for in a flight attendant?

How do you use your checklist? Your FO doesn't use his checklist. What do you do?

What do you do to prevent complacency?

If you lost your medical, what would you do?

A big thanks to my friends who gave advice as well as anyone who ever posted anything on the compass interview!

Arrive at Pan AM Flight Academy by 8:30. Someone will greet you and get your log books and have you fill out a piece of paper with basic info (name, address, phone). When I interviewed there were three of us. We were given a schedule of events for the day, which consisted of different times for each candidate. First off, there is a short presentation by HR on the company, benefits, etc. Then you start the interview process which consisted of: Sim eval in a 727 sim (visuals and motion off). Basic maneuvers, climbing/descending turns at constant aispeed (always 1000 fpm up and down)and steep turns, enter a hold. Written test, 75 ATP questions directly out of the test bank. There were no calculation problems or questions that refered to a chart of graph. Panel interview which consisted of the HR rep, and two previous NWA pilots. Questions consisted of tell me about an emergency you had. What are some of your strengths that are not on your resume, how would you handle a situation where the FO was not adhering to SOP and when you said something he ignored you. What is the best flying job in your opinion. Where else have you applied. How do you see the rest of your career laid out?It was very conversational and laid back. There is a paperwork session where you fill out all of the PRIA forms, DOT drug test paperwork, drivers registry forms, etc. You are fingerprinted and a picture taken for your name badge is done at this time. The last thing is they buy you a cab to a medical clinic and you take a drug test. The pay for a cab from the clinic also. I left Pan Am at 1:00, I had to wait on the drug test for about an hour.
Compass will positive space you to/from MSP. You are responsible for hotel and transportation to Pan AM.