Looking at the classes as they are, though, I see that this is not neccessarily the goal for D&D Next. I'm not saying that the character needs to get a new feature at every level, just something. This could be the bump up in Weapon Attack Bonus, or a bigger expertise die, whatever.
By their very nature, the caster classes do gain something every level: a new spell. But what about the martial classes? Well, let's take a look.
NOTE: from here on out, I'm going to give vague descriptions of stuff from the playtest, since I believe me using the very specifics are against the NDA.
Skipping level 1, because you get something from that no matter what, we see the fighter gets a bigger expertise die and a new maneuver at level 2; NOTHING at level 3; a Weapon Attack Bonus increase, additional expertise die, and a new maneuver at level 4; NOTHING at level 5; a feature at level 6; NOTHING at level 7; bigger expertise dice and a maneuver at level 8; a Weapon Attack Bonus increase at level 9, and additional AND bigger expertise dice and a new maneuver at level 10.
This makes it so the fighter gains 2 things, then 0, then 3, 0, 1, 0, 2, 1, and 2 things when it levels up. That's a bit inconsistant, and can really make certain times of leveling up better than others.
"Well," you might say, "how well does it line up with the Character Advancement Table for gaining ability score boost, feats, and skill boosts? I bet the better ones of those line up with the worse ones of the fighter."
I would respond with "NOPE!"
In fact, two of the times that the fighter gains nothing from the class, it lines up with the other table giving NOTHING.
A very similar thing happens with the Rogue class as well, I don't really think that I need to get into that.
BUT! I have a solution to the problem. First, I edited the Character Advancement Table to give 1 thing at each level, making that table very smooth. The downside is that by level 10, you end up with 1 fewer skill boost, unless WotC is willing to put one in at 1st level. Also, if the original table and my table continue with the same pattern all the way to level 20, you end up with 1 fewer feat as well. I think, in the long run, it won't make much of a difference, though.
Here's my new Character Advancement Table:
1 - Background, feat
2 - Skill Boost
3 - Feat
4 - Ability Score Boost
5 - Skill Boost
6 - Feat
7 - Skill Boost
8 - Ability Score Boost
9 - Skill Boost
10 - Feat
The biggest difference is that Skill boosts were switched to odd levels, rather than even. The other was that, instead of one feat every three levels, you get one every four levels. But, like I said, that doesn't reduce the overall amount of feats except by 1 by the time you hit level 20. I kept ability score boosts the same, since that felt like it was a bigger balance issue to be messing with, plus it lined up in my table anyway.
Now, for my new Fighter Table:
1 - Front-Loaded

2 - Increase Expertise Die (ED) size
3 - Additional ED
4 - Weapon Attack Bonus Increase, Maneuver
5 - Increase ED size
6 - Feature
7 - Additional ED
8 - Maneuver
9 - Weapon Attack Bonus Increase, Increase ED size
10 - Maneuver
Unfortunately, I couldn't do it completely evenly, since the Weapon Attack Bonus Increases kind of got in the way no matter what, but they're also sort of the 'lamest' feature gained anyway, so it's okay to overlap them with something else.
Those of you who look at the official table and compare it to mine might notice that, when it comes to expertise dice, my table ends up being a bit more powerful in the middle, but it starts and ends at the same power levels, albeit, a little sooner in some cases. I found it strange that 1) They didn't increase the expertise dice AT ALL for 4 levels. My only guess is that they thought the feature was too powerful to be included with an expertise die increase. 2) They seem to make up for it by increasing the size AND number of dice when going from level 9 to 10. So, the precaution becomes moot later on. My table has a steady progression, swapping between die size and number of dice each time.
My new Rogue Table:
1 - Front-Loaded

2 - Increase ED size
3 - Maneuver
4 - Additional ED
5 - Weapon Attack Bonus Increase, Maneuver
6 - Increase ED size
7 - Maneuver
8 - Additional ED
9 - Maneuver
10 - Weapon Attack Bonus Increase, Increase ED size
The Rogue has similar changes to the Fighter, but the even and odd levels are kind of swapped. This makes it so that the Rogues ED progression is one level behind the Fighter's (for levels 3+), which is a good thing in my book. The Rogue should probably be just that one step behind. That also helps balance out the fact that I ended up giving the Rogue an additional Maneuver (which gives it an equal number with the Fighter) in order to actually make a repeatable pattern. You can remove the Maneuver given at level 5, but that destroys the pattern. That might be okay, though, since if you continue the patterns of the Fighter and Rogue, the Rogue will actually have one more maneuver than the Fighter at level 16+, since the Fighter would likely get another feature around then.
But it's tough to speculate about what's after level 10, especially since WotC says they're working to make high level play very different from normal.
For the record, I spent probably about 2 hours doing calculations and rewrites of all this. You don't even want to see my notes for all of that; they would take a great deal of explaining.
Anyway, I just wanted to put my 2 cents in. I don't want dead levels and I want progression to be smooth, not jumpy.
