is dota is good game?

Think you're in the wrong subforum. I can't say if its good or not but imo I just don't like it. I tried it recently and it was pretty difficult. Though, that's just learning a different MOBA in general. Why not just try it yourself and see?

It seems to be popular with people who get salty and conclude that they're too good for LoL.

It's more difficult to get into than LoL, and there are mechanical differences that make it significantly more skill-intensive if you want to get good at it. (For example, every hero has a "turn rate" which means you can not instantly turn around like in LoL. This makes kiting as a ranged hero virtually impossible, which is why "orb walking*" exists.)

*Orbs are a type of on-hit CC, such as Frozen Mallet's slow (Eye of Skadi fills this niche in DotA 2). DotA 2 also has a CC called "bash" which is like a very brief stun, and mini-bash which will interrupt casting and auto attacks iirc.

You can always just play against bots to give it a try. Their bots are infinitely more complex than LoL bots.

It's a completely different game.

Like Harry Potter and LotR are both fit into the fantasy type of books they are completely different beyond that.

Give it a try and see if you like it.

Heroes of the Storm is a good game.