Atonement is very different to Enduring Love - in fact Atonement is unique amongst McEwan's work in its scope and themes (its relative length is indicative of the wider scope I think). To be honest I don't think that characterization is McEwan's strongest area, but he certainly makes up for it in other departments; the energy of the opening of Enduring Love, the atmosphere and description of Atonement, the insightful look at parenting in The Child in Time, the political commentary of Saturday, etc. Also, whilst he doesn't create characters with the precision of someone like Dickens or Dostoevsky, his characters' interactions always seem incredibly authentic (which in my opinion is a greater quality than pages and pages of personality description, and paradoxically gives a better insight into the characters than a long description might).
I would definitely recommend you read Atonement. People often single it out as the only McEwan they really enjoyed which is unfortunate because, whilst being excellent, it is not typical of him.
Out of interest, you say you felt the main character (I take it you mean Joe rather than Jed or Clarissa?) lacked a personality. Do you not think this is perhaps intentional? The opening of the book says a lot about Joe; he is middle class, comfortable, rational, loves his wife etc, but there is a shift away from this and the book is ultimately about the effect of Jed on the lives of Joe and Clarissa. It's less that he doesn't have a personality (or that McEwan can't be bothered to write him one) and more that his whole existence is thrown into turmoil by Jed's obsession with him. Also, he is a rational scientist and not prone to long, profound musings which might offer insight into his character. To apply what I was saying before about interaction of characters (as opposed to "characterization" as such), Joe is written in stark contrast to his wife who is a Keats scholar (Keats being a "Romantic" poet whose work transcends the rational and scientific.) The symbolic difference is played out in what happens when they are faced with the outside influence of Jed. If you're merely saying you found Joe a boring-seeming person, then I actually agree - but that's hardly the point! The reason I recommended Black Dogs is that it is slightly better on classical characterization whilst retaining McEwans ability to pit ideologies against one another convincingly and enthrallingly.