My question to the reader is, do you think the essentials classes are too powerful compared to their latter classes with the miss effects that they gain, or are they just more powerfull now compared to say a two bladed ranger with lots of feats and a paragon path at lvl 11 when they are at 11?
I haven't seen Essentials classes in action at higher levels, yet, just in Encounters. The basic-attack martial builds could fall off in relative effectiveness as other classes get more daily powers, but more likely, they'd just be 'overshadowed' in the sense of drama and spotlight time, not in the sense of actual overall contributions.
Compared to the PCs that were going through H1-3 when those modules were brand new, yes, they're going to be more powerful. Games like D&D inevitably experience some power inflation as more material is added on, and there was some very rappid output in the first two years of 4e. A non-Essentials party, built with the full range of 4e options available prior to Essentials would also seem pretty powerful going through them. Also, if your group's been playing 4e for a while, you're better at it than you were when you first tackled Irontooth.
But, Essentials character classes, more than being 'more powerful' are sort of in 'easy mode.' It's not that a Knight is more potent than a Fighter, it's that an indifferently played Knight is every bit as potent as an expertly-played Fighter (and hardly behind an expertly played Knight, either). This is true across the HotFL classes. If you compare them to their PH equivalents, they aren't a lot more powerful, but their features perform at full power more consistently.
The Knight & Fighter, to start, both mark (though the Knight doesn't call it that) and punish adjacent enemies for defying that mark. The Fighter marks the enemy(ies) he attacks, and has a variety of choices for encounter multi-target attacks, making him able to mark a lot of enemies, some of the time, and his mark punishment is 1/round, so, when marking multiple enemies, he may sometimes decline mark punishment against one to retain the threat of it against another. The Knight, OTOH, marks all adjacent enemies, all the time, regardless of when or how they became adjancent, and his mark punishment is 1/turn, so he can take it every time his mark is ignored. In theory, that makes the Knight 'more powerful,' but, a very well-played fighter can generally have the right enemy marked at the right time, with mark punishment threatening him, and be just as effective. The Knight just delivers the same performance as a flawlessly-executed Fighter, but with very little effort on the part of the player.
Similarly, the Theif and Rogue both do extra damage when they have combat advantage, and gain an extra bonus when using certain weapons. The Rogue gets a +1 with the dagger. The Theif gets it with all his initial weapons of proficiency. The Rogue can get combat advantage by flanking, which requires going into melee, and, often, braving OAs and getting flanked in turn. The Rogue can output a lot of damage, but takes risks to do so. The Theif can use Ambush Trick and Tactical Trick to get CA, every round, of every fight, at range (if he didn't happen to pick those up, he can also get CA from Fortune Cards), CA just comes effortlessly, so he's always outputting high damage, with little risk or effort. And, the Theif gets his SA per turn, not per round. (Though, unlike the Knight/Fighter mark-punishment, this has been errata'd for the Rogue, too).
The Slayer gets not a per-turn damage bonus, but a per-attack striker damage bonus, and gets his weapon talent with all weapons. Very potent, very simple. Not much else to be said about the Slayer. There are some outre CharOp builds that use dagger-wielding Sorcerers to capitalize on a similar damage bonus to MBAs in a broken way. The Slayer prettymuch does that out the box.
The Knight and Slayer also get 'power strike,' an encounter power damage boost used /after/ a hit, so it's 'never wasted,' rather like a reliable encounter power (which is a pretty rare thing).
It's not just the Martial classes. The Warpriest gets riders on his attacks that are comparable to what the Cleric gets, but are in Effect lines, rather than Attack lines.
The Mage gets more 'targets enemies' AEs than the Wizard, which has many 'all creatures' AEs, and the Mage's encounters all get 'miss' or 'effect' lines, so they're 'never wasted.'