Last time I tried it was riddled with performance issues. Does anyone know if it's safe to upgrade yet ?
You can simply upgrade to 3.8 instead of 4.2. All the improvements in JDT, PDE and related tools are the same, but you do not get the new CSS styled, modeled workbench, which is mostly responsible for the performance issues.
See this answer for a more detailed explanation: https://stackoverflow.com/a/12381204/44089