Yes, read them all. It's difficult in a longish series of books like this not to be a little samey, but I genuinely enjoy these. There are ongoing threads (like his 'missing' wife) so PJ has to backtrack in each book to bring new readers up to speed. My sister lives in Brighton so I have a sort of affinity with the locations.
In general there are lot of book 'blurbs' that state, '...when a headless body is found......' Investigative detective novels are age old, tried and tested, so it's not easy to come up with anything truly original - most don't! But there are some crackers. In my opinion the best ones rely on strong characters. Roy Grace is one, Harry Bosch is another, as is Rebus. They are all slightly anti-establishment and flawed.
I've just finished, 'Eyes of a Child' by Richard North Patterson which was really good.
I've had a go too.......
http://abargeatlarge.co.uk/