As you already mentioned, it acts solely as a prodrug of phenmetrazine and isn't active on its own (see: European Journal of Pharmacology 2002, 447(1): 51). Hence, it makes no sense to snort, inject or plug the stuff. Psychoactive effects develop slowly after oral consumption, I'd say between 20 to 40 min, depending on the stomach content. A low dose is around 10-30 mg with effects lasting for approx. 6 hours. A medium dose is between 30 and 50 mg with effects lasting for ca. 10 hours. Even higher doses are possible, but pointless IMO, as the magnitude of the effects doesn't rise proportionally in this region. The duration can be extended to max. 14 h (without additional dosing).
The effects equal the ones of 'plain' phenmetrazine with the only significant difference that they come up much slower. The sometimes cited description of a 'clean version of amphetamine' (ie. less sweating, less pronounced bruxism and peripheral vasoconstriction, better control over chattiness) describes it quite well. Due to the slowed upcoming of the effects is there next to no euphoria.