I have read the first 27 books in the series so far. I have enjoyed the vast majority of them, they are fun reads that I mix in with my usual reading. Like the Axler books, there are multiple authors on the series, some are better than others, but they all have produced entertaining stuff, and I am glad that I have read them.
Mel Odom and Victor Milan have written quite a few in the series, You might be familiar with their work if you have read a lot of DL/OL. Odom penned my favorite, Forbidden City, and another favorite, Paradox, was by Milan. I have not reviewed any RA books yet, I wish I did.