You misunderstood Jeffe. He didn't say that tech was worse, just that it wasn't as fancy looking.
And sorry, no. The little of the novels I've read are complete and utter crap. I haven't seen a single worthwhile thing come from any of the novels. ANY complaint you have that is grounded on information from the novels is going to be scoffed at by me. Just a warning.
And even if you think the prequels were even worse (which I don't, yes, there are some awkward bits, but the mythology is actually quite good, which is not somethign you can say for the novels). Plus it has the virute of having been produced/released by George Lucas, not just by his permission, which means that whether you like them or not, they're canon. It's a silly argument to make though, because your complaint itself has to do with ratifying what you've read into the what you've seen in the movie.
Again, the tech is better. The X-Wing can beat the snot out of previous fighters. It's a MUCH better fighter than anything you see in the prequels. Likewise the Star Destroyers and Super Star Destroyers: bigger better faster more. Nothing like it before. And yes, they're clean, as is the Death Star, unless you're making the irrational complaint that the trash compactor should also be clean.
The rebelion's stuff looks junkier because it IS junkier than standard tech. It's patched together hodge podge of whatever they can get. so none of it looks as nice and shiny.
The factories and the command center on Geonosis on the other hand, which is the head quarters of an alliance that spans tons of systems, including the two richest organizations extant (the Trade Federation and the Banking guild) looks like trash. Completely. the Trade Federation command ships don't look any better than command ships seen in eps 4-6.
Bespin is pretty sharp looking. At least as clean cut as Naboo. You could argue Naboo looks niftier, but keep this in mind: Bespin is a MINE, which is inherently dirty, and the entire thing is just tech. Whereas Naboo is simply stone buildings that they've been able to make all over the place.
Plus, motion picture special effects have improved in the decades since the original trilogy was made, so Lucas can do cooler stuff -- which is the real reason it looks that way.