At nearly two months old, The Burning Crusade Classic gets four-stars, because the game that was built for the time and space it was built for still stands phenomenally strong when compared with any modern MMO.
The game is not filled with obtuse and meaningless systems that don't lend to the vision of a great MMO. Things make sense, earn gold, work on professions, earn gear that actually matters. Players are wearing the gear that you see, classes balance and design is improved from Vanilla Classic, Heroic dungeons are at their most difficult point in WoW history and for good reason - as Badges of Justice will transition from a progression system early-on to a robust catch-up mechanic naturally throughout the course of server growth through content releases.
The raids are iconic, colorful, fun, and have mechanics that are USUALLY visually intuitive enough and require many or all players to participate... even if the standard gamer is more aware and has better tools in 2021.
The original arena maps show their age for those used to the newer retail textures. As exists all throughout TBCC, there are some one-off issues that the developers COULD slowly resolve over time. Hitbox issues with the tomb in Ruins of Lordaeron, the Nagrand tornado not having a diminishing return etc. - but arena lives and dies on the back of CLASS DESIGN... and Burning Crusade classes despite SOME unfun mechanics here or there (see Sonii sitting in sheeps / novas for more than half the match in the recent tournament) ARE hands down better and than retail classes. Far less homogenization makes for strong identity, and interesting internal mechanics and abilities allow for some nuanced gameplay, as opposed to flashy visuals played out on a script - at least in PvP.
Pace of combat is also very strong. This will change over the course of TBC, with less tank mitigation and lower player health pools early on. Caster dominance is apparent in the early tiers, but melee will come in later, and in the case of PvP - things WILL slow down with additional stamina and resilience. MANA MATTERS.
It's clear that TBCC and retail WoW (currently Shadowlands) are hardly related in design terms. This enhances Blizzard's ability to appeal the same IP to different audiences with different tastes for design philosophy. TBCC has been under threat of losing this core element however. Paid boosts to skip the intended leveling and growth process to get you attached to your character, a "store mount" to undercut the aesthetic value of achieving a unique cosmetic, rampant gold-selling & buying (in some cases due to botting).
This four stars is being gracious, and if untended to the game could slip further down, but TBCC also has more potential than any MMO currently released to become king - BECAUSE of the solid design philosophies that built the original game.