Update (Mid 2016): D54250WYKH – This old (2014/2015) model has serious hardware issues related to USB, Display and SATA interfaces. Some this issues not resolved even after BIOS update. Please refer the Intel NUC forum to understand more this. To minimize the issues, you can run the unit with-out any keyboard, mouse and monitor. But still SSD/ HDD related issues might pop up.
Today I brought one Intel NUC for experiment purpose. Totel cost is ~1K SGD (NUC-i5, 16GB RAM, 250GB mSATA SSD, 1TB 2.5″ HDD).
Performance is okay. Remember not to compare the NUC processor (less speed and less cache) with regular i5 processors. Max RAM is 16GB. Tested with Win8.1, Ubuntu 14.04 and running few VMs also on it. Slit lag during heavy operations like starting VM. Otherwise okay.