This thread is intended to address, in a comprehensive manner, the current position of Marksmanship in BfA. Since Blizzard has repeatedly said that tuning passes have not yet been done, I'll be specifically focusing on mechanical issues and features, along with proposals to fix them (derived from several of the very long MM threads here and in the Class Development section), though I will also be noting significant tuning issues as well. I'll be modeling this after some of the higher quality feedback posts made recently for other classes/specs.

Core Issues
The baseline rotation works reasonably well. However, it has some issues.

Aimed Shot's cast time. Many players feel the base cast time is too long, and causes the entire rotation to feel slow.
Unbonused Arcane Shot damage. It feels low, and makes steady/arcane filler feel unrewarding.
Rapid Fire as a generator. This prevents it from scaling with mastery, making it fall behind as gear improves, and causes very weird playstyles with focus management, especially with talents.
Lack of a power-feeling signature shot. Rapid Fire is arguably the closest to that, but it doesn't have the same powerful feel as a true signature shot (Chimera Shot or Windburst, for example).
Precise Shots feels weird in AoE situations. Multi-Shot doesn't consume it, meaning you either have to waste the buff, or weave in single-target Arcane Shot casts during AoE.
Sustained AoE feels problematic. Aimed does a LOT of damage with Trick Shot, but once you're out of charges, you're basically reduced to spamming low-damage Multi-Shot.
Trick Shots requires 3 targets to activate, but the Rapid Fire effect is clearly intended for 2-target cleave. The limited AoE range on Multi-Shot can at times make triggering Trick Shots an issue even in AoE situations.
The RNG in the base rotation is extremely low. The only RNG is the number of Precise Shots charges you gain from Aimed Shot, and that's of very limited impact. Talents that add RNG have extremely low proc rates or no rotational changes associated with them.
Many talents in general feel very low impact, either because their effects aren't terribly noticeable or because they have extremely low proc rates. We also have AoE talents competing with ST talents.
Our primary cooldown, Trueshot, doesn't feel as impactful as other class CDs, and requires a very specific set of conditions in order to use properly (no Aimed Shot charges, enough time and focus to cast Aimed Shot before you get another charge, RF not coming off cooldown before you get off that first AiS cast).
The benefit of Haste feels low. It doesn't affect the cooldown time on Aimed Shot or Rapid Fire (a departure compared to most classes), meaning that increased haste simply increases the percentage of our time filling with Steady and unbonused Arcane. This leaves haste as being pretty darn terrible for us.
Lone Wolf is currently not worth using due to damage balance and pet utility
Moving between targets while soloing can involve a lot of waiting because our passive focus regen is so slow.

Detailed Analysis
Aimed Shot
The cast time on Aimed Shot is easily one of the most commonly complained about elements of MM in BfA. Players often assert that it makes the rotation feel slow, and leaves the hunter vulnerable to necessary movement (and a loss of the entire cast time so far) for significant length of time. Aimed Shot currently represents the longest non-talented hardcast ability in any DPS rotation in BfA. Chaos Bolt has the same base cast time, but is almost always cast with the 30% reduction from Backdraft. The only two talents that provide similar or longer hardcasts (Destruction's Soul Fire, 4.0s cast, and Fire's Pyroclasm, 4.5s cast) involve intentional talent choices and only occur once every 30-45 seconds in normal gameplay. Marksmanship uses AiS an average of once every 12 seconds. This cast time, along with the dominance of AiS casts and AiS-based effects (Precise Shots, Trick Shots) in both our single-target and AoE rotation, is a very commonly cited source of MM feeling "slow" in BfA.

A common recommendation is to drop the base cast time to 2.5s and adjust Arcane Shot damage to compensate for the slight increase in filler GCDs per minute.

The state of Marksmanship