Resin kits range in quality from Midship Models at the bottom and JAG and Admiralty at the top. They are generally less detailed in the molding than plastic kits.
On the other hand, the hulls and superstructure are using molded as one big block which allows for relatively seamless construction.
With the addition on PE etc. They can be very nice, and the selection of kits in resin is MUCH larger than plastic.
They do come with some challenges though.
1. Resin is harder to paint. Many acrylics don't stick well to resin and require priming and sanding
2. Resin (unlike plastic) expands and contracts with heat. So, you MUST use Gator Glue (or other flexible glue) for railings and the like as they will warp with the hull movement if you use non-flexible super glues.
3. Resin dust can be toxic, so be careful if you have to sand it a lot.
4. Resin kits usually cost more than plastics.
With all that said, don't be afraid to jump into resins if the subject ship is of interest to you. With all the aftermarket PE and items for ships these days, there really is no reason not to start with a resin kit and trick it out. Feel free to check out my library of kits in my gallery. Many of them are resin and will show you a wide range of quality in kits. PM me for any specific questions.