Fully rewriting my review at this point now that I've sunk a lot more time into it and the devs have ironed out all the server limit issues.
This game is genuinely awesome. 40 dollars for a PVE experience that can be filled with absolute laughs amongst friends or incredible moments that make you feel like Super Earth's strongest soldier.
The multiple difficulty tiers feel reasonably balanced as a whole, the multiple tiers might seem initially off-putting but it allows for players to fine-tune the level of difficulty they want from the game without having it feel too hard or too easy.
Progression is formatted like a battle pass system which might seem initially off-putting but the devs have stated that all passes are permanent, and the free pass has 3 times the content of the first premium pass and a majority of it is really good for late-game content. Not only that, the pass gives you plenty of premium currency to buy armor from the shop or save up and buy the premium pass, so the game doesn't feel pay to win.
The only major complaint I'd have with this game is it's weapon balancing. A few weapons in the game will be used exclusively into the endgame, but the disparity between the good and bad weapons is so huge its not even funny. If a weapon its bad, its unusable even on lower-difficulties with how unsatisfying they feel. The game needs a balance wave to boost other weapons to the same level as the weapons that are good, hopefully without nerfing any of the good weapons. Armor also needs to be properly fixed and working, but the developers are aware of that as of this review's writing.

It's a very fun MOBA and the fact that the spotlight it got was to be a spot for free Overwatch skins during a rough phase in the game's life cycle is a travesty.
It's the MOBA with the most balanced roster of characters. There are definitely some characters that are better than others when it comes to the level of complexity versus the reward given by playing them, but nearly every character in this game is viable. HOTS also has the most unique roster mechanically; a majority of the characters you'd see in this game (Cho'Gall, Abathur, Stukov) would never be considered by Valve or Riot in the modern day.
The biggest downsides to HOTS would likely be the maps and Blizzard themselves. The maps in HOTS revolve much more around playing objectives than in other MOBAS, and some of the maps have grabbing objectives effectively making or breaking the game you're playing instead of giving a skill-based advantage. As a result, the gameplay on these maps can be jarring going from laning phase to a sudden objective phase, as giving up said objective would result in a huge disadvantage. Blizzard, in unsurprising tradition, sucked when it came to balancing this game when they were still actively updating it with being reliant on trickle-down balancing (making tweaks based purely on the pro-player level and hoping it'll change the game competitively and casually for the better).
Also Blizzard didn't nearly add enough Starcraft content which is at minimum 2 points docked.