i've been playing a dk at level 90 for less than a week, so my experience is not werry good, so what i'm about to say may sound totally retarded to an experienced dk.
but in a stressfull pvp situation, like arenas, i like Runic corruption a lot more than Blood tap, because instead of focusing on spamming frost strike for the stacks, i like the passive effect that can accur every time i use one frost strike.
i'm playing 2h frost btw, and i rarely find myself in a situation where i'm both rune and power starved. lining up my burst i can easyly tear down a healer in a few seconds in any 2v2 arena, with 100k+ obliterates.
i also find unholy blight with Chillblains in a combo with remorseless winter to give some nice cc, have countless times taken on 1v5 fights in bg's, and getting out alife after killing 1-2 players in the few seconds my cooldowns allow me to. The combo basicly slows everyone around you so much that only a few players can get out of it, and followed by 5 sec aoe stun they are helpless against my burst dmg, especially when i play with my hunter friend.
but again, that's just words from a newbie frost dk