Amps are a bit like cars, really. The new ones have lots of computers in them, and working on them can be anywhere from daunting to an outright PITA, but by and large, they'll do most everything you could want them to as well as or better than the "classics". And of course, some people will gripe about how they can "tell" that a car has electric instead of hydraulic power steering or that a car is throttle-by-wire, but we tend to ignore them. Same with the folks who can tell that it's not a "real" amp.
The older ones, by comparison, are simpler to work on because there's generally just less to mess with, but they also are a bit fussier and generally require more upkeep with parts that are becoming harder to find. Some people will still swear they're better. Guitarists and gearheads are rather obsessed with outdated technology in that way.
As for me, I have owned two Line 6 amps (the Spider series, even) and have no complaints. I think people are just expecting too much out of them - for $300, you aren't getting top-of-the-line DSP. You just aren't. But I can definitely see myself with a modeler at some point in the future.