That quote seems fair enough to me. The general premise behind putting all welfare payments into one makes a lot of sense, but the devil is in the application (as always). I can't say I know a great deal about it, but there do appear to have been a large number of mistakes made in the application of it. Whilst politicians can't be absolved from blame, the civil service will be the ones doing a lot of the application of this, so they should shoulder some responsibility too. Having done some work in a few government departments, the level of input from the minister is pretty small, yet they're largely the lightning rod for any criticism of the service that the civil service deliver.
It's easy to fall into the trap of thinking the Tories are evil, therefore replacing them would instantly make universal credit work, but the civil servants would largely remain the same whomever is in government. I mean what would Labour do? McDonnell has said they would scrap it, but then Chakrabati says it would merely be tweaked (and renamed). It seems a likely stepping stone towards UBI or something of that nature tbh, so I can't see AN Other party scrapping it, and I'm not at all sure that AN Other party would be better able to manage the civil service roll out than the Tories have been, as the people actually doing it will be the same.