I am pretty excited about D&D 5th Edition as it is, and mostly I only have minor complaints. The only larger problem I have, is the way how proficiency levels are done. Characters are either really good at something, or can't really grasp at it. Everything scales off from your levels. No middleground, no real choices when making a character. Class abilites enhance certain skills in some cases, but its far less common to make any real variety between characters who are not overly specialized. Yes, a Rogue sneaks better than a Fighter who happens to have stealth, but there isn't any difference between a Bard and the Fighter.
Another problem, fighting classes have no real advantage in combat than non figthing classes. A fighter can hit just as well as a wizard can, given they are using the same weapon.
Of course, if you are not interested in making characters more detailed, and you prefer the streamlined solution provided in the core books, more power to you. But if you are like me, and would want just a little bit of more crucnh and mechanics... Here it is, Proficiency Levels, Optional Rule
Proficiency Levels -- Optional Rule
The goal of this optional rule is to make a difference between skill levels, and make them scale not only from character level, but also, the level of proficiency. In order to achieve this, we will introduce 3 different levels of skill proficiency. This applies to weapon, skill and tool proficiencies but not armor proficiencies. The skill levels are the following:
Novice: The character uses half of his proficiency bonus
Journeyman: The character uses his full proficiency bonus
Master: The character uses 1,5x of his full proficiency bonus
Any time characters gain proficiency from any source, racial ability, background, class, feat etc. they gain 1 level of proficiency instead. These levels of proficiency can stack. If the character has the option to choose multiple different skills, weapons or tools from the same source (like a background) he may not choose the same twice, gaining a higher level of proficiency.
For example, a High Elf would gain novice proficiency in Perception, Longswords, Shortswords, Shortbows and Longbows.
If he took the Fighter class, he would gain novice proficiency in all Simple and Martial weapons, but since the proficiency levels stack, his Longsword, Shortsword, Shortbow and Longbow skills would be Journeyman level, gaining full benefit from his racial powers, while all other weapons would be novice. Also, he has the option to take two skills from the Fighter skill list, and since Perception is also present, he has the chance of enhancing that ability further as well, for the price of having less skills.
About balance: This optional rule will affect game balance a bit, and it assumes that the players have the option of taking feats. Earlier in the game, the characters will feel less powerful, but if they choose to invest in feats that give proficiencies (now these feats make a lot more sense), they will become adept and then later a bit more powerful than usual, but since this is quite taxing in feats, it shouldn't be a problem. Most characters will have a few focused abilities with Journeyman proficiency, and one with Master, and the rest is novice. Characters will be more specialized, and the difference is a lot more noticable between two characters.
Additional stuff: If you implement these rules into your game, you can also add the following optional rule:
Backgrounds give weapon proficiencies: Some backgrounds will now grant weapon proficiencies that make sense in context with the background.
Criminal: Club, dagger
Folk Hero: Quarterstaff, Unarmed strike
Noble: Any two martial weapon
Outlander: Any two simple weapon
Sailor (or Pirate): Scimitar, Trident
Soldier: Any four weapon