I liked a lot of his solo stuff, but he does tend to go too near to parody with the obvious love he has for Motown.
In 1986 I saw Peter Gabriel on the 'So' tour, which is to this day, the best concert I've seen. The next weekend I saw Genesis at Wembley Arena (Invisible Touch tour), and they just bored me to tears. The low point was when Collins donned 'Blues Brothers' hat and shades for a 20 minute medley of standards..it was bloody awful, and the crowd was baying for Genesis songs (unsurprisingly).
Having seen the sister documentary to 'When In Rome', from the reunion tour in 2006(?), 'Come rain Or Shine', he does indeed come across as a complete tool, and obviously didn't want to be there at all.