But if you're talking about the several novels that "finish" the Foundation series, I've never read them, nor will I ever read them.
The 'Second' Foundation trilogy doesn't finish the series so much as, er, not finish the series. It's a series of prequels, or rather mid-prequels; three books set between and around the two prequels already written by Asimov. Not convoluted at all, then.
They were written by Bear, Brin and Benford, who are all quite respected hard SF writers. They're not bad, but the three authors consciously chose to adopt their own tones rather than emulate Asimov's, so they don't quite 'fit' into the series' atmosphere. On the plus side, they do add quite a bit of texture and technology to the universe, particularly regarding life on the sprawling capital city/planet of Couresc- of Trantor. On the other hand, they feel a bit peripheral and unnecessary most of the time, as if they've been shoehorned in. I still found the three very entertaining, particularly the second, but I'm a sucker for anything that goes into a bit more detail about R. Daneel.
The third also manages to neatly propose an escape from the consequences of Foundation's Edge, which, I recall, quite impressed me when I read it. This was some years ago, I admit.