In-editor terminal? ^Z or :shell (Asking for an in-editor terminal makes about as much sense as my whinging that Eclipse doesn't have an in-terminal editor)
In-editor debugger? I admit this is less than ideal.
A REPL? Languages suited to REPLs have REPLs, and a lot of them support SLIME, allowing me to interact with the REPL from vim. For everything else there's tmux.
Build system? :make and errorformat
SCM integration? ^Z. Or fugitive I guess. (a third party plugin, yes. But if you think it's ho-hum, you probably haven't used it).
An in-editor debugger?
Does it offer a REPL?
Does it work with your build system and your SCM system without some ho-hum third party plugins?