I'm following the development of the Scala IDE somewhat closely and report now and then a bug. The plugin gets better and better - there are still some quirks but there are workarounds for that.
For me it works best if I use the sbt compiler via command line in parallel to using Eclipse in order to hunt down compile errors, since sometimes the IDE does show misleading information. This proved itself to be a good approach over time.
Maybe I would get less problems if I would use a stable released version? It speaks for itself If I can use the nightly builds without much hassle anyway ... :)