I like Brennan Manning's books; they're thought-provoking, well-written, and have useful and interesting anecdotes spread throughout the text. They're also very honest, making no pretences about the author's past, and his descent (more than once) into alcoholism.
'The Relentless Tenderness of Jesus' is a book about the nature of God, particularly as seen in the person of Jesus. I didn't find it as powerful as 'The Ragamuffin Gospel' by the same author but it was still very readable, although at little heavy in places. I read it over three weeks, though it's only a little over 200 pages, but there's a lot in each chapter.
I didn't find it 'unforgettable', as the blurb on the back says, but then that means I'm all the more likely to re-read it in another year or two. It's certainly something to make people think, particularly if they've never got beyond basic or fundamentalist ideas of who God is. Paradoxes are confronted, and horizons expanded.