I haven't been disappointed by the endings of his more recent novels: Cryptonomicon, Anathem, Seveneves. (I did not enjoy time spent on REAMDE, that being the only exception.)
Of those 3 I was only somewhat happy with Anathem. I couldn't finish REAMDE and Seveneves convinced me that I may not read another one of his books again, unless it debuts to unanimous critical acclaim or something similar. I thought the ending of Cryptonomicon was pretty weak but the rest of the novel leading up to it was so fantastic that I didn't care. Honestly I found the Baroque Cycle to have the best ending of any of his works, and I would describe it as the one time I was happy with both the journey and the destination of a Stephenson novel.
Of those three I was initially least interested in reading Anathem. Maybe as a result, I was most pleasantly surprised by it. Agree that none of these compare to the Baroque Cycle.
Seveneves was frustrating because he spent hundreds of pages setting up a premise worthy of an entire lifetime’s worth of books and then just...stopped. Any other author would write that book and be set for life. Neal Stephenson has no time for that and just moves on to the next pile of ideas in his notebook.
It's definitely a prequel (REAMDE, that is) but you can actually see the story of Dodge taking shape through it. Having said that, Dodge could have been about 300 pages too long..!