Pros
As far as travel and expense booking tools go, it is number one in the market. With contracts with the US government, french government, and big companies such as google, microsoft, boeing, jp morgan, and american express just to name a few, Concur is dominant. The corporate culture is good. There is work life balance, everyone is friendly, and the benefits are good. 21 paid time off days is quite generous.
Kontras
Concur is using an obsolete technology stack and is not making any progress toward getting rid of it. Its a career dead end for developers. There are over a million lines of classic asp in the legacy code base with thousands of new lines of vbs added every month. It is quite spaghetti. Very few people understand it, and even people who have worked there for many years can't answer questions about features that they wrote. New hires are going to struggle and spend days writing one line fixes for simple customer cases, because debugging the code is a nightmare. It is not cleanly structured, meaning business logic and UI logic are mixed together inside functions that span thousands of lines. There are no coding standards or conventions in the asp code base so even reading it is difficult.