We had a very laid back and addon-less ICC10 run last night. Lots of silly pulls, people not knowing their class changes (hello there Mr DPS DK in blood presence!) and 8 bosses killed. With that in mind, here are some thoughts.
1) Shield slam is amazing. Simply amazing. With a full stack of vengeance and the heavy repercussions talent my shield slams are 16k - 20k during shield block. That's without inner rage. That is also NON-CRIT. I had a 37k non-crit shield slam on Festergut last night with 7 stacks of gastric bloat. The new shield slam is awesome once you stack vengeance to sufficiently high level. Since my other attacks were hitting for up to 7k I think, shield slam is a huge proportion of our dps now and catching those SnB procs is vital. I can't believe they won't nerf this.
2) The new heroic strike is really good - I like the fact that you don't wait for the next weapon swing, but it's just an instant whack in the face that's off the gcd. I have incite so it crits pretty often, and it hits hard enough to feel like a proper meaty attack. I need to get into the rhythm of hitting this button every 6 seconds instead of every 1.5 seconds and deciding when to cleave, but currently it feels like a positive change.
3) I've always liked cleave-type attacks, and with the glyph of cleave being major rather than prime, it's now available for prot warriors. Cleave therefore hits three targets and is pretty great for AoE pulls. Revenge still hits hard and the "revenge cleave" is still lovely for big pulls.
4) Single target threat isn't too bad at all. I didn't have any problems last night once I'd found out where all my buttons were and got my UI in order. It's definitely no longer straightforward to keep aggro on multiple mobs, but if people are following a kill order it's usually ok. By the end of the raid I was no longer losing mobs on AoE pulls, but of course if someone was going single target there would normally get aggro.
5) Rage generation was fine when tanking. When not tanking I still felt like I had enough rage to use a decent spread of abilities, although as ever having to drop revenge from my rotation in those circumstances was annoying.
6) I suggest that you don't bother with rend or blood and thunder, and that you ignore thunderstruck. A cookie cutter 31 points in the prot spec will have 4 utility points - I went for gag order (even though it's not particularly useful at present) and hold the line (which was up about half the time I think last night).
7) Thunderclap's been nerfed quite a lot. The damage is pretty poor (although as noted I haven't specced into thunderstruck) and so even though it does a lot of additional threat you'll need to tab target and cleave to keep aggro.