Hi Trenk,
Good Sam's coverage is good in the sense that they're not a fly-by-night company that's going to go out of business after taking your money. They also have a pretty good reputation for living up to their terms and conditions.
As you consider this policy, it's good to understand how the coverage works, how the deductible plays, the fine print on what's covered and what's excluded, and to have some view of your risks if you don't have coverage.
There are many repairs in an RV that fall into the several hundred dollar category. A few that are more expensive.
When our trailer was new, I bought a 3 year plan from Good Sam, with $250 deductible. When the 42" TV broke, they asked me to get an estimate on repair. Turned out the cost of repair was $200, which was less than the deductible. So they paid nothing. When I had damage to one axle, it was among the excluded items. They paid nothing. When the refrigerator needed a new cooling unit, Dometic provided the parts for free even though out of warranty. I paid $250 deductible and a few dollars for incidental charges. Good Sam paid a little under $600 for labor. Had Dometic not provided the parts, Good Sam would have paid around $1800 additional for the cooling unit.
So as it turned out, Good Sam ended up paying me back just about what the policy cost, and except for the goodwill gesture from Dometic, would have paid back 4 times the policy cost.
There's an argument to be made that I could have saved my money and self-insured. It would have come out ok. On the other hand, if Dometic had said "sorry, you're out of warranty," it would have been very expensive for me to have self-insured.
My advice is to read the fine print and if you decide to go forward, set the deductible at a level you're ok with.