Any good at what ?
As a singer, his voice has improved with age and experience. Probably most important was the discovery that they could write songs in keys that suited his voice, rather than sticking to keys that didn't use black notes as they had with JD and early NO.
As a lyricist, Barney is capable of flashes of brilliant insight and simple yet effective structure. He is also capable of absolute garbage. The quality control button sometimes gets stuck ! Let's just be grateful that the live lyrics don't get onto the record, as your lovely Savile sleeves would suffer from Tipper Gore's little stickers.
As a guitarist, he's probably a lot more competent than he ever allows himself to seem - all the songs are structured in a way that affords him minimal live work. Some of the JD stuff showed a theoretical understanding (the blues E scale in NDF came straight from a book), but there has been little straying from the basic use of barre chords.
As a complete songwriter, he is one of the most innovative and unheralded writers of the last 25 years. Never forget that Barney is the melody man, the provider of most of your favourite tunes. Hooky and Steve have their own roles in the creation of a New Order/Joy Division song, in terms of format, patterns etc, but Barney has been the main tune writer. Some of the stuff is entirely his own work - Temptation for example. Take a look at some of the complicated arrangements on Electronic to hear what he can do - the majority of that album was written by Barney as solo during 1989 before hooking up with Johnny Marr.
In a nutshell, he is a genius songwriter and producer, with a real talent for sound creation and development.