My experience with Concur is that the product itself is not bad. Not great but not bad once you get used to it. (Fir example, there's a lot of random information asked for that varies by category which is annoying but you get used to it.) The problem is with the auditing on the Concur side, whoever's "fault" it is.

Things like any date discrepancies between the receipt and how it's entered on the report get bounced even if they're off by a day even though it's obvious and, pre-Concur, would have just been fixed in-house. Also random invocations of travel policies cause rejections rather than not just making a trivial connection. Simply not reading comments with respect to exceptions. Etc. I'm sure hundreds of hours of highly-paid people's time gets wasted.

Which is the classic startup story of you need to build your product for the user that is paying your bill. Even if that means subjecting the actual end users to misery…

Concur is painful to set-up but once it's done, it's not too bad