I have played Beastmaster mostly solo up to level 16 in the Underdocks.
I am very bored of the class and I am going to reroll.
This post is about what I don't like about Beastmaster.

Forced to play Two-Handed

I feel forced to play Two-Handed because the damage is much higher. Maul is not appealing enough compared to Chop. Having to choose between different abilities based on the weapons we use is good, but my fights are twice as long if I play dual wield. So the 5% mitigation from Maul is simply not enough, especially if it lasts only 5 seconds.

Some numbers:

With Hagrul's Skullcracker (DMG 13, ATK Delay 43), Chop deals on average 35 damage, and auto attacks deal around 30 damage.
Command: Kill deals 10 damage which is similar as pet auto attack, and never crits.
With Hagruls'Tenderizer (DMG 7, ATK Delay 30), Copper Dagger (DMG 5, ATK Delay 22), Maul deals 5 + 4 damage. The auto attack seems to be around 20 (15 + 5 or 5 + 15), mostly crush and no pierce, but always 2 hits. So the auto attack definitely seems competitive since it also has a better attack delay. But Maul is insanely low damage.

Forced to play Guardian Spirit

My damage is much higher than my DPS pet, I would say pet is more around 20% of my total damage (it is a level 15 wolf). I played with Savage Spirit for a while, but my damage being much higher now, I am forced to play Guardian Spirit if I want my pet to maintain aggro on a single target, otherwise every time I use Savage Strike, the mob is hitting me, which becomes very problematic if I am on a dangerous pull with 2 targets.

Boring rotation

Engaging Strike -> hit and buff for 30 seconds -> this is the must use - prebuff ability
Savage Strike -> hit and get bonus damage if target is bleeding -> this is the "filler ability"
Chop -> hit and make pet land critical hits -> use on cooldown followed by Command Kill
Command kill -> ask pet to perform a very low damage attack - should synergize with Chop but is not doing critical strike ?

All the damage is coming from 3 different hits, but they do not have strong class identity, they all are hits that feel the same and make the class lack personality.
Yes for complementary skill, no for the fact that they are all "strikes/hit". There should be some "bite", "scratch", maybe stances and what they do should not just be raw flat damage with a tiny buff/debuff. I also think their animation matter and could improve the feeling of playing the class.

Lack of utility skills

Utility skills is what I think can distinguish Beastmaster from other class and make it more fun.

Example: Scroll Aquatic Affinity (level 28)
Attune yourself to aquatic beasts, increasing your Swimming skill by 20 and decreasing your air consumption by 80% for 1 hour.

It is a cool skill, but why such a skill that is tied to our class identity by its description is only available at level 28 ?
I think the class could be improved if there were more "beast/nature" themed buffs available at early levels so that the player falls in love with his class.

Maybe with more quality of life skills that makes the class feel unique, I would have stick on it.
But in truth the main reason behind my reroll, is that the DPS rotation is boring to me, and that I cannot pull a single mob without pulling everyone (this is more of a game design choice I guess).