Bonus is not stable - Avis employé Software Engineer ThinkPower

You can learn how to work with the other team members

low pay, low tech, hard to learn high level skills

You might learn different know-how from various cases and customers. There are due dates or mile stones in most of cases, that might let you get a sense of accomplishment after finish each case. (It is distinct to some very long term projects.)

If you developed the products for customers use internally, you probably can't tell others what product you have built directly. Sometimes you might have to follow some strange rules of customers.