Captain Pedantic to the rescue!
Rep: "+" (as in plus sign) means higher level. "x" (as in multiplication sign) means bigger amount of mobs. Maximum amount of foes without increasing the level: +0/x8.
SS is in my opinion the strongest melee powerset, overpowered due to factors that either elude most people or that they choose to ignore. 
Namely, Foot Stomp's radius, Rage buffing your tohit to absurd levels and your damage significantly (which essentially means any pool or epic attack will perform, out of the box, roughly ~25% better on a SS character than on most other primaries, and that will jump up to ~50% once you doublestack it) while being an easy to use, reliable click as opposed to a mob drain, KO Blow's range, damage and secondary effects, and the rest of the set being actually decent with KDs all over the place - hype would have you believe SS is balanced around perma-Rage, but if you take a look at the damage per recharge/endurance you will see SS powers are in line with similar powers from other primaries.
I've found the lack of AoE to be really noticeable in the late twenties. 1-20 flies by fast enough, but by level 25 and up until 32 I often find myself in situations where I wish I had an AoE. Possible solutions to alleviate the problem: use any XP boosting paragon reward power you may have in that level range. Sands of Mu. Spring Attack. Those are band-aids, but once you get to level 32, it's all worth it.
Driving myself a little bonkers trying to figure out what I want to do at this point. So far this is what I've managed to play through trying to pick. All of the following were paired with Willpower (my favorite set ^_^)
Choice A: I got a Kinetic Melee character up to ~23, got into the SO's, was having a good time in general other than the fact that I found Burst rather lacking in the AoE department. I mostly wanted KM because of the -dmg effect it had on my target. Worked very well for a "wind" magic using character since KM does look a bit like swirling wind. The entire set just didn't seem...right? I don't know how to explain it, I felt like I could do more. I understand the set is not perfect for brutes, but it was still adequate. Not the best, but it didn't seem bad, just lacking. I really wish this set just didn't feel so off, it's fun to look at.
Choice B: I jumped on the band wagon and tried Street Justice, got her to 22 fairly quickly, and wow was I unsure what to think. I love the single target DPS, it was wonderful, but it's AoE capability was even worse than KM. I didn't read Spinning Strike well enough and realized it wasn't a PBAoE but a small targeted one based on my target. Considering I enjoy running +8/+3 (or is it +7/+4? It's the one that gives you more mobs rather than stronger mobs, I forget which) I tend to get surrounded so the AoE was to useless to make it worth it.
Choice C: I tried Stone Melee, got to 22 again, finally gave up just because I thought the set was ugly. Strong yes, and fault was tons of fun, but I just couldn't stand looking at it.
Choice D: Tried fire melee, realized I lost one of the AoE's when moving from tank to brute, said meh, left the set alone. I was never really all that fond of the fire set anyway, just adding more DPS with no other benefits has always been questionable to me.
So yea, that's been my path so far, and now I'm not sure where to go from here. I hear lots of good things about Super Strength but having to wait all the way until Tier 9 for your AoE? Granted it's a great looking AoE no question. From what I understand you can cancel the defense debuff of rage crashing once you can double stack it so that's not a big deal (2 level 50 IO's and a few LotG, which I have sitting on a bank mule, so not so bad there). I suppose I would be almost forced into hasten, at least if I want to be able to easily stack rage at a lower level (hasten + 2 recharge DOs = barely double rage).
SS is also the last power set that I can see that has a good PBAoE effect. I may have overlooked one but that seems to be it.
So how does SS perform? I'll still be using Willpower of course. I can see it would most likely pick up at 32 with foot stomp, but how slow going is it up until then? Any advice at this point is appreciated, even if it's not quite directed at SS/WP. I'm just having a serious block as far as what I want to play.
Also, since it may impact it, I am generally grouped with my fiance who will be running a Cold/Sonic defender.