Ice/Ice/Ice baby ...
From my perspective, Ice is a different creature. You can easily max out your defenses (sans psi/toxic). The best way to play ice/ice/ice is, as a tankcontroller.
You understand Hoarfrost (dull pain), but to add:
1. Chilling embrace - Causes your enemies to have -damage, -recharge, and -slow (or is it +slow ...). Pop a slow IO (or the slow damage proc, if desired). Why? See #2
2. Hibernate - Hibernate is your get out of jail free card. First, you do NOT have to wait until you have 100% recharged your health and stamina. This is a nice duality. Your foes are suffering slow effects from chilling embrace. You are hit with massive damage, and need a heal. Hit Hibernate. The taunt of your aura's will hold them a long time (I think 13ish seconds). If some blaster out aggro's you, they will still have the -run speed (slow). I believe it lasts 13 seconds (the taunt aura), which should be enough for hibernate, heal, pop out, taunt, etc. Hibernate is very useful esp for alpha's . For the CW king, I got hit by the psi blast. Dropped very low on HP, and healed up with hibernate. Before I went in, I told the team, to wait until I got aggro. If the team listens (big IF, but mine did), they will wait an extra 5-10 seconds. Very useful with hard hitting AV's (bobcat, in incarnate TF ...).
For ice melee:
I believe damage was added to frozen aura as it was the most worthless power ever. From memory, it should do footstomp level damage but its all COLD (less resisted). The sleep is a nice side effect, and allows slotting sleep IO's (e.g. Placate (not sure why a tank would ever slot placate (PvP maybe??), chance for -recharge, or chance of self heal). This was a spectacular win for ice melee, which, as you can tell, is sub par damage-wise.
Ice patch - Ice patch enables the 'other' form of damage mitigation: knock down. Unlike regen/healing/resists/defense, this relies on the time an enemy is incapacitated (knocked down then getting up). With chilling embrace -recharge, you can greatly reduce the incoming MELEE damage (does nothing for range damage).
Freezing touch - A good hold, and does damage. Best paired with a hold APP, you can even hold bosses and elite bosses (again if memory serves). Add a few attacks with a proc %chance to hold, and you are holding the baddest of the bad (you wont hold entire groups like controllers, but you are far more survivable than them).
Taunt - many forget, it also has a -range component. VERY useful to bringing in those outside your aura's, inside your aura.
frost - gives -recharge and -slow, doing haymaker (pure cold!) damage in a cone! Works well with chilling embrace. To get the MOST out of it, pop in 2-3 hami dam/range. From experience, the default range is too small to be effective beyond a single target. I popped 2 in there, and was surprised at how many more are affected by the cone. Best use of hami damage/range is melee cones, imho. Go around a corner when herding, and give them a frost blast for fun and giggles.
app: hold (discussed), range, shiver (-recharge, -speed!).
Strengths:
1. Defense can be capped, easily (sans psi/toxic)
2. Hoarfrost can be perma, allowing massive regen/HP.
3. Lots and lots of -recharge, slow effects
4. Some -damage.
5. Can perma-hold bosses (singular).
Weakness:
1. Not good at mass herding. the -slow will make it painful to herd them doggies! Hint: make it a habit to turn off chilling embrace then on. This will help, but other powers will cause slows.
2. Not good at burst damage. I HIGHLY recommend tough and the 2 +resistance IO's (should put you around 32%). Lots of IO's have +SL resistance (I have an SR tank near 75% SL resistance, but I build for that).
3. Damage is not great
I recommend going dual build for ice/ice/ice (doesnt have to be expensive).
build 1: group tank (add recharge, keep hoarfrost perma, and add +SL resists, and feel free to add some hold procs). Get tough. Feel free to get weave, since it will only cost 1 power anyways (tough requires kick/boxing).
build 2: more damage!
But, you can do both, with some compromises.
Depending on how you play, ice tanks can be surprisingly fun. As a group tank, you wont have massive damage, but you will reduce most attack rates to zero, keep them close to you, and hold any big bosses from hitting you (in case of freaks, ice patch is the great equalizer). I prefer going with the tanktroller role. Its unique, novel and more active in tanking. Plus, your damage is pure cold, not smashing. You will do better damage than a rage-less super-strength tank (rage makes SS great), have LOTS of control, and options to survive, while keeping your team alive.