Pros
easy to get a position, next to impossible to be fired, true academic environment if you are into that, you can put Dr. on your doorbell and as your preferred salutation elsewhere after you graduate
Cons
As a PhD student you will be expected to work full time even though you are paid part-time. Because of part-time assumption your payment is quite low for a person with a master degree ( 1.2-1.3 kEur/month netto). Expect about half of the pay you will get on junior position in the private sector. No dedicated educational program, or consistent policy of investing in personnel training. As there are no strict policies on supervision - big portion of that full-time and overtime work is in vain, just to learn on your own mistakes. You are a cheap labor, no one cares about wasting your time. It does not improve your ability to land a good job afterwards. Master graduates who who wrote their thesis in the institute have similar jobs as the PhD graduates several years later.