I think they're great. Love a good Dive Machine, me. And I still think Oblivion is by far the best. It's the best because it's so short, because it's all about the drop. The Oblivion experience starts when you see the thing for the first time, and continues as you approach, join the queue, watch the queueline videos, board and climb the lift hill. The culmination of all that, the climax, if you will, is the vertical drop into the pitch black hole in the ground. To pad it out with inversions, helices and airtime hills is defeating the object.
To this day, my first go on Oblivion 20 years ago was the probably the scariest thing I've ever done in a theme park, and even though I personally don't find the vertical drop scary anymore, I can still appreciate how intimidating and imposing they are to first-time riders. Whenever I feel like I'm getting bored of Dive Machines, I just cast my mind back to those first few rides on Oblivion and all those feelings of terror and anxiety come flooding back.
So, I'd say they were underrated by seasoned enthusiasts, simply because the fear factor isn't there anymore, but to newbies and the "GP" they're still bad ass coasters.