Pros
Colleagues with a high expertise in the language and the different popular domains the language applies to (e-commerce, websites, CMS, custom development).
Good for gaining your first work experience, bad financially if you'd stay for 3+ years.
Cons
A high pressure environment when working on internal projects, when you are placed at a client as a consultant this might not be an issue.
The wage is not conform to the market rate. To give some examples; someone with 4y experience will earn a gross wage of 2270 euro/month, someone with 13y experience will earn 3200/month.
Negotiating a wage increase is difficult since there is always the excuse that you need to get a certain certificate and that your current wage is similar to the others in the company (sad if true).