So far Diablo III patch 13 feels neat with the introduction of the revamped Runes system. I will miss how the old runes looked like with the colored spheres, but it was merely a concept in our minds. Beta testers never got to experience that system, so it won't be missed for long.
In the current rune system, which beta testers can now experience hands-on, the runes are no longer items that drop from bosses or monsters. Every few levels you get access to a new rune for a specific spell.
I don't particularly like the idea of not being able to choose which rune and which spell I want it into, but I'll keep testing. Each rune for each spell is gated by a level requirement up to level 51 (when the game goes retail) which gives you a pace for the length of time till you reach level cap. In that regard, it feels a bit like World of Warcraft (pre-Cataclysm).
Basically, the old rune system was bogus and flawed in a specific aspect -- in order to test what each rune could do for X spell, you had to keep replacing it with each of the rune types. Now that's a waste of runes, and there was no way to figure out how often these dropped to justify such a waste to satisfy our curiosity or to test which play style was of our liking. Also the fact you won't remember which rune did that cool effect I liked a month ago.
So now each spell has a tab with all available runes. You can pick the rune you want -- for as long as it's available at your level, and switch back and forth for testing purposes until you decide for a somewhat permanent one.
Check out our screenshot gallery to see some of the rune variables per spell.