It's true that Consider Phlebas is set outside The Culture. I think that's for the best as The Culture is pretty alien and the Phlebas protagonist is more relatable. Banks does a great job of building the world such that when you get to the end of the book, you're like "I get it" in terms of understanding the Culture. Plus, Phlebas has a number of wonderfully evocative set pieces that are super cool. You can see how influential the series was on later sci-fi, especially stuff like Halo.
It’s a very human story, and the technobabble intervenes very little in it. It also has the most connection (of the Culture novels) to our world, being largely a meditation on the first Gulf War. This makes it the most approachable, in my opinion.
It is technically a sequel to Consider Phlebas but the connection is almost nonexistent, no prior knowledge of the Culture-Idiran war required.
i like the culture books but they suffer sometimes from jumping unreoated viewpoints, mental instability, and sprawl sometimes.
player is tighter and doesnt jump. probbably a better entry.
sorry auto corect and swype tuened off mid post so speley misteaks
The downside is that it's quite a bit different from (and imo a bit worse than) the other books and could mislead you about what the series is like - or even turn you off entirely.
If you're already committed to reading the entire series, I'd start with Consider Phlebas. If you're unsure, start with The Player of Games.
(I saw Look to Windward and Player of Games recommended. I'd say Look to Windward is probably more enjoyable once you've read Consider Phlebas, and Player of Games is perhaps a little... simple, compared to the others? I don't remember having much doubt of roughly how it would end)