I have owned, at some point or another, many kits...and I can't really bash, nor praise the work. It's VERY hit and miss. Also, my brothers have bought the same ride, only to have the quality substantially better or worse then the same model I bought.
Zipper- other than trimming the excess from the boom, it wasnt that bad. The cars also need trimming, my biggest issue there was the drill holes in the tubs were crooked.
Kamikaze- Looked OK, actually never finished it, as Ron only supplied me with one tub lol
Ring of Fire - Really decent base model. Getting paint to stick to the ring it the hardest part. Lots of sanding and priming. Overall a nice model
Convoy- also decent, once again, its mainly trimming excess from the resin
Hamptons.....not too bad. the cycles I received were really bad though, pretty sure my brother is working on them now.
There are others, that I just said "forget it" on....I can't really say anything good or bad about them, as I never put the effort into them.
I will always classify RAH models as "base" models, meaning that you get some parts, and the rest is really up to you. Does that make it OK that the kits are sometimes of terrible quality? Well not really. I guess among ourselves here, we all agree that they are models that need a lot of extra work. I'm happy RAH makes the kits, as I am not all that great at scratch building.
Even at the moment, I am considering buying a couple of kits. Most likely a Zipper and some other parts. Do I look forward to all the work that I'll have to do...nope...but I know I can't 100% scratch one, so for 25 dollars, I at least know what I'm getting.

Justin