Yes, not exactly hot-off-the-press, but in the field of biblical studies 'new' does not necessarily mean 'better'. Of this little book Schweitzer opined:
'It belongs, not to theology, but to the literature of the world'
I'm hoping for similar comments on the back of my first book...
Wright: "Chris' book makes the rest of us look like we didn’t purposefully write our books at all, but merely randomly jabbed at a keyboard for a while"
If you read Schweitzer's classic, The Mysticism of Paul the Apostle, you will start to get a feel for the importance of Wrede. You can find an able summary of Wrede's Paul in a chapter of S. Westerholm's Perspective Old and New on Paul.
Yes, of course, Wrede's book is seriously dated in many respects and some of his conclusions will seem naive to many modern readers, but if you wish to attempt a history of research on Paul in the 20th century, there is no better place to start than with Wrede's Paul.
By the way, against those scholars who emphasise the importance of social-scientific categories and social developments as if this should stand over against Paul's theology, as if concerns with Paul's theology were merely the preoccupation of a 'history of ideas' separated from the real stuff of scholarship, think on Wrede's words in his author's preface:
'[I]t is in [his] theology, to a very great extent, that the historical importance of Paul is to be found' (vii).