Solution stand-up time is very fast. Our company's extremely rapid development needs were easily met using The product. Out of the box to a working solution took only days, where some of the other products that were sampled would have taken far longer.
I can't really find anything I dislike, but there was an issue handling very large XML files. The fix took a bit longer than I would have like. However, the issue did not prevent our company from meeting the aggressive deadlines we faced.
The problem we faced was using SSIS to translate the complex XML schemas, which proved to be disastrous. Data Integrator allowed us to easily, and very quickly, stand up a solution at a VERY reasonable cost.