My aunt used to bring raw guarana powder back from time to time when going to Brazil, and always gave me some, but it's been a while since she went there. I still have a small amount somewhere - but not sure if it's still suitable for consumption.
The effects were pretty nice, very comparable to cafeine, but you're a bit but more focussed, active for a longer timespan and have no real withdrawal symptoms when not consuming it for a day or 2 - unlike cafeine, but that could just be due to my cafeine consumption, never consumed as much guarana, and almost always, it was combined with cafeine throughout the day.
The taste wasn't all that, I ended up making tea from it, mixing it with orange juice or even redbull or coffee. When going out, combining it with a small amount of alcohol kept me going all night without ever having the need to go for "other" stuf, while still being able to function pretty normally the next day.
Combining with alcohol is probably not that healthy, and you have to be careful with the doses when dealing with raw powder - but probably a lot better than the illegal alternatives (although at that time, guarana's legal status was unclear).