I like what it does for me I've used them, but now I just buy L-Arginine which does the same thing, supposedly theres another compound that goes with Arginine but I can't remember what it does or what the name is, I feel like I get decent pumps with it and will use it with creatine when I come off cycle for a boost. It also makes you look fuller, since its used to increase circulation. Overall I wouldn't say using it for longe periods of time is worth it just because supplements can drain your pocket without enough of a benefit to be worthwhile.