I agree that the quality dropped, but it is up to the reader to decide whether a chance to revisit old friends is worth the fact that they aren't up to snuff. For me it was marginally worthwhile a couple of times. For others it is not. But I won't tell others not to do what I did.
Black Gold comes to mind as the best of the later books. Asterix and the Class Act I've meant to read for a while as the stories were written by Goscinny.
Of course the English translations rely a lot on Bell and Hockridge. They are absolutely masters of the pun.
I agree that the quality dropped, but it is up to the reader to decide whether a chance to revisit old friends is worth the fact that they aren't up to snuff. For me it was marginally worthwhile a couple of times. For others it is not. But I won't tell others not to do what I did.