I have to disagree. While they are always polite(to the point of not looking human), they tend to not read the entire ticket and make assumptions without checking facts, which leads to providing blatantly wrong information and misleading or confusing the player.
They are also very limited by Riot's policies in a way of what they can or can't do, up to the point of inability to solve many cases or answer a wide range of questions that you can reasonably expect to get answered in other games.
I used to work in shared hosting support and I know several people who are tightly connected to bank support. Stuff like that would unacceptable in these spheres on multiple levels, but, I guess, is fine in a F2P video game.
Does it mean that support is good and deserves praise?
No. The support is bad. From what I've seen, it's really, really, really bad and something as standard as Blizzard support incompareably outclasses Riot's one.