What’s behind the widespread negative response to Wild Sorcerers, and how can I ensure they’re fun at my table?

I’m just starting to get into D&D 5e. Magic classes in particular fascinate me, and the one that caught my eye the most is the wild sorcerer. Or, rather, the concept did. The mechanics of the design itself seem particularly lackluster when compared to every other magic class I’ve looked at.

After quite a bit of searching, it seems I’m not alone in this observation. All over the place, people insist that wild sorcerers are unbalanced/underwhelming/generally unwanted. But I haven’t really seen any explanations of what exactly makes them this way, compared to other classes.

I’m now looking at attempting to DM a game with a bunch of other newbies, and trying to figure the game out as a group. One of my players will likely want to play a wild sorcerer. I’m interested in seeing how that plays out in RAW, but more importantly, I want the players to have fun.

I’m new and inexperienced. What should I look out for in the Wild Sorcerer when considering balance, or fun? Are there any gaping flaws in practice for the wild sorcerer’s design?

Right now I’m considering using the existing mechanics, but supplementing them with a secondary system of character progression that slowly takes the sorcerer from fearing their magic that’s unpredictable, to having some, but not total, control over it. Basically there’s a chaos level that increases and decreases based on player ability/spell usage. High chaos means more wild surges, low means less. To get the most out of the design, you have to balance the chaos level (in theory).

Note, I’m well-aware that I should probably stick to RAW during the learning phase. But as someone that works in gaming, I’m also aware that mechanics typically function differently in practice than in theory, and so I want to be prepared for any known “in-practice” shortcomings.

It sounds like the main ones are how often a surge happens (GM overhead, chance of anything happening at all), and exactly what happens (more flavor vs more functionality, which is up to what you want from the game). Both answers were solid, but I’m going with Icy’s, since it approached the question more specifically targeting the Wild Sorcerer’s in-practice functionality with examples and edge cases.