I like EJ very much, mostly Tones and AVM - and to a lesser extent Venus Isle. After that I did not keep track (though I saw him live few years ago).
I think his songwriting skills are decent. More than that actually. There are quite good songs on Tones (Bristol Shore, Friends, Trail of Tears), not overwhelmed by too much guitar wizardry. He’s obviously not in the same league as Paul Simon or Joni Mitchell etc… but when you think about it there are very few great guitar players who also have solid songwriting skills. Most guitar greats would come with awesome riffs for sure, but not so many would write good songs. EJ surely could/can do that (and other than EJ I’m thinking Francis Dunnery can be good too, but I can’t think of many others).
His voice is an acquired taste but to me it perfectly fits the songs. Interestingly enough he sings in a similar register as his old friend Christopher Cross. A heavy-metal vocalist would sound very bad with Eric’s music IMO. A female singer on the other hand would be a nice match.