As I started the "How good is Steve" thread I'd better add to this one hadn't I?
I think his best work is the JD stuff. If you take just the two albums and the two singles there is an evolution in styles and sounds which is pretty impressive in such a short time span.
Transmission, New Dawn Fades, Shadowplay - simple, powerful riffs, great chord progressions that really drive the songs but also delicate picking - see mid-song NDF which is beautiful.
On Closer these elements are still there but for a large part of the album he is experimenting with feedback ridden, choppy fills and repetitions that create that - dare I say it - a wall of sound on stuff like Atrocity Exhibition.
I guess with NO they wanted a new sound. Keyboards and Sequencers taking over and he did say he couldn't sing and play at the same time - so the guitar took a backseat for a few years. That said, Hooky did step forward and start providing the melodies so it worked out nicely.
He probably is much better that he makes out but his interest appears to be in creating music rather than being a Guitarist.