Overwatch's newest Hero, Brigitte, is a rather interesting take on the usual array of healers that have appeared in the game so far. For the first time, you can play as a healer who can survive a respectable amount of damage while dishing out a fair amount of damage of her own. In fact, the most efficient way to play Brigitte is to be on the front lines, swinging away with the Rocket Flail and triggering the Inspire effect for your allies. Given her unique playstyle, Brigitte can enhance the performance of a number of existing team compositions, but her lack of versatility compared to the other existing healers also leaves her with a few glaring weaknesses.
Brigitte's most obvious weakness is that, compared to the rest of Overwatch's healers, her healing capabilities are rather pathetic. While everyone else can heal more or less on demand, Brigitte has to damage someone to trigger Inspire, which gives nearby allies 16 health per second for five seconds. For reference, this is more or less the same effect that Lucio's healing aura has, but given that it's conditional, it guarantees that Brigitte can never be regarded as a primary healer. Brigitte's Repair Pack is far more impressive, capable of giving an ally 150 health and up to 75 points of naturally decaying armor if they are already fully healed, but its six second cooldown is excruciatingly long. Thus, if you really want to make an enemy Brigitte useless, use Heroes who have long range and high burst damage. Pharah, Bastion, and Junkrat are some of the more obvious examples of Heroes who can stay out of Brigitte's range (thus preventing her from triggering Inspire) while dealing more damage than she can heal.
Conversely, Brigitte's comparatively high durability and defensive utility among Overwatch's healers makes her an incredible asset against Heroes who rely on whittling their opponents down, especially at close range. Winston for example would have an extremely hard time diving a team if Brigitte's Repair Pack is ready to go, to say nothing of how he's getting flailed, stunned by Brigitte's Shield Bash ability, and or knocked back several meters by Whip Shot. Genji and Tracer are less affected thanks to their high damage potential and mobility, but it still forces them to play around Brigitte since getting stunned by Shield Bash is no laughing matter. It should also be noted that Brigitte's shield prevents Zenyatta's Orb of Discord from acquiring targets much like Reinhardt's shield, though obviously on a much smaller scale. McCree and Soldier: 76 are undoubtedly going to have a very annoying time trying to kill Brigitte seeing as how they can't easily maneuver around her shield's 600 points of health, but at the same time, if Brigitte is trying to shield herself, then she can't really heal anyone else.
In the grand scheme of Overwatch things, Brigitte would thus be a more niche healer than initial impressions would suggest, especially once her novelty wears off. She obviously can't function effectively in Tank-heavy team comps since she lacks the damage, durability, or utility needed to replace Lucio, Moira, or any Tank. Brigitte would also be an extremely awkward pick for a traditional dive comp since she has no mobility, and she certainly can't replace Zenyatta since his Orb of Discord is vital to the success of dive. A slower, barrier-centric team comp involving Reinhardt, Orisa, or Zarya might have use for Brigitte on account of her shield and Repair Pack, but with only so many other healers that she can effectively pair up with (Mercy, Moira, and Lucio to a much lesser degree), you would essentially be trading versatility for a mild enhancement of the team comp's natural strengths.
In an anti-dive team comp however, Brigitte might find the most use. It would simply be near-suicidal for D.Va and Winston to dive a competent team with some combination involving Brigitte and Reaper, a good McCree (good being the key word), or Junkrat. At the same time, Tracer and Genji will just have to accept that they can't expect a free kill on another team's healers in such a situation, forcing them to shift targets to a DPS Hero (which could be dangerous) or a Tank (which could be too time consuming). A good team running dive still has the advantage of mobility and can get crucial kills before anyone can react, but Brigitte makes it harder for them to do so when she presents at least one less easy target and can prevent another from being an easy target. Of course, Brigitte certainly has her uses in a less specialized team comp (which is more than can be said for Doomfist), but it's probably not enough to shake up Overwatch to a significant degree.