The effects really depend on the dose. I have quite a bit of experience with Phenobarb, and I find that in small doses, around 50mg-60mg, it has effects very similar, to Diazepam, and overall quite boring. However in doses of 100mg+ it gets much more fun. It feels like being drunk with a clear head. It's better than all benzos I've tried with exception of Flurzepam and Temazepam. Do not snort them. Snorting them is an absolute waste, especially with their long onset of action and high oral BA. Some barbiturates can be quite boring, while others like Seconal and Amytal can be even better than heroin. While you can get away with mixing opiates/alcohol + benzos, mixing barbiturates with any deprressant = suicide
EDIT: Barbiturates have a unique effect because at larger doses they act as "direct agonists" of the GABA-A receptor, where as benzo and alcohol just empower the function of GABA-A. At very large doses (overdose), barbiturates block the ionotropic glutamate recptor, and that combined with their "triple depressant effect" (agonist, GABA PAM and kainate inhibitor) causes respiratory arrest and death.
Some barbs are more dangerous than others, Nembutal being the most dangerous one. I have not tried it, but I have tried Secobarbital, and when I took it orally it was great, but when I IVed it, it was awful, you can read it here:
http://www.bluelight.org/vb/threads...enced-Awful-and-scary-Secobarbital-experience