The company is currently hiring at many locations across the country. They are actively recruiting with head hunters and recruiting agencies. I have seen their recruitment booth at professional conferences. They have a high turnover so if you want a job with them and they have no current openings, just wait a while, or sign on as a PRN staff. You could also consider a travel position.
Morale is currently not great so I would recommend Matrix as a "job" rather than as a career. It would be a good position for someone between jobs or someone moving to a new area, or for a new grad to get some experience. It would also be good for someone who moves frequently. It seems that their highest paying jobs are in management rather than as a field NP.
While working at Matrix, I have found that I have lost my edge for prescribing and following my primary care patients. You can however be exposed to more medical conditions and thus potentially expand your assessment skills. (I am getting better at hearing murmurs because of the population that we see.) It is a great opportunity to work independently. The job is actually a little like detective work -- can you come up with all of the members' diagnoses based on their meds and their version of their medical history and then provide enough proof for it, all while you are sitting in the members' home and ideally in less than an hour? It gives you good practice at history taking but just remember that the history may not be in the format that you would normally use to take a history.
If you are thinking about interviewing at Matrix, just ask lots of questions about the position, ask about the pros and cons to see what the recruiter has to say and then think if it works for you. You may even want to ask if you can tag along with a current employee to see what the position is really like! You can always go PRN before you take the leap. I would definitely suggest the last two suggestions if you are at all undecided.