My take on the subject in my most objective point of view:
Pros:
The music feels different, and somewhat more inspired than their last 2 Portnoy efforts (SC and Black Clouds).
The band seems happier now.
The band doesn't feel anymore like a monarchy.
No more 'forbidden' songs. The band's catalogue is available for live performance anytime.
JLB stepped up as the true frontman of the band. This was necessary.
Cons:
Fan interaction has suffered. Greatly. It's been months since we had any true updates or anything new to discuss about, and that makes me forget about DT for a while (thing that never happened in the Portnoy days).
The setlists don't feel as smart and as well thought out as Portnoy's. BTFW's setlist is nice and the inclusion of songs like SDV was amazing, but the flow isn't as nice as a SDOIT era setlist, for example.
The 30th anniversary setlist sucked mostly, which is kind of a wasted landmark. Their 20th Anniversary World Tour was so amazing in all aspects that this mini-tour was extremely underwhelming. I get it was a festival tour, but it wasn't what I imagined it would be. Some of the least representative songs of each album were played with no flow whatsoever between the songs, which would never have happened with Portnoy me thinks.
The band feels more like any other rock band nowadays, and doesn't feel as special as I felt they were back in 2006, for example.
Sound quality of their albums. There hasn't been a truly amazing album production-wise (both live and studio) since the Portnoy days.
I'm kind of 50/50, and I love Mangini but I do feel the band lost something deeper than its drummer. I will still see them live any time I can and buy their albums, but I'm not as crazy about them as I was back in 2010.