It's the most ambitious Smash game and the only one I actually loved.

Brawl was a gamechanger. Now that's not taking anything away from Melee. The moment-to-moment physics are better in Melee and Melee was a big step-up from the original. With Brawl, we got so many firsts for Smash..
-3rd-party characters
-A story mode with a lot of cutscenes
-Custom stages
-A massive library of music (for the time)
-Assist trophies
-Final Smash
-Online. Ok, well the online sucked. And the online has pretty much sucked since. But it is an option.
Brawl was in many ways, the first modern Smash. Now I'd rather go back to Melee because of the moment-to-moment gameplay and larger differences to Ultimate compared to Brawl.
But for me, every Smash after the original is amazing (unless you count 3DS on its own, but that's still an excellent release).
Tripping is just about the only complaint I have about Brawl.

Outside of tripping Brawl was pretty much perfect. I prefer it to Smash 4, which despite being in HD, having 8-player battles and a larger roster felt like a smaller game.

I tried so hard to like Brawl, but went back to play Melee and the first version instead.
The less technical slowed down gameplay took out most of the fun for me. It never felt intense. Even with added moves, the diversity in ways to control the characters felt lacking.

I get that a lot of people like the single player experience, but that was never a reason for me to play smash.
The final smashes was a nice aesthetic touch that expanded on the characters lore.

Is it a bad game? No, not really. It is packed with content and polished to the creators intent.
Do I like it? Not one bit. No other game comes close to the number of hours played not enjoying the experience.
This game, in combination with the Legend of Zelda Phantom Hourglass, is the reason I no longer give games a chance if I do not enjoy them the first few hours.

The opening sequence alone makes it an amazing game by itself - and I’m only half joking!

Not in any universe.

Depends on what you want out of it.

I'd wager almost anything that the player in question you're referring to was a competitive Melee player, and if you came into Brawl hoping for a similar experience to Melee, with a high skill ceiling and lots of movement options, then you'd likely be disappointed.

That said, if you're just approaching it as, well, more of a casual party experience, you'll probably love it. It has a broader variety of stages/characters and a much more involved story mode to boot.

https://www.vgchartz.com/games/gamereviewdisp.php?id=6962&reviewid=97

Brawl is still a fantastic game but I do understand why Melee lovers (I'm one of those) don't like the changes to the physics compared to the more intense fast-paced nature of its predecessor. Just for fun here's my ranking of the series:
1) Melee
2) Ultimate
3) Brawl
4) Wii U/3DS
5) Smash Bros (N64)

Brawl is the only Smash game I bought and kept, mainly due to the Subspace Emissary mode. None of the other versions ever had single player content like that. If they would flesh out that mode with more intricate level designs and enemies it could even be a released as an independent title.