For $400, it's likely a good deal - problem being there's not enough information to know what the deal actually is, there's no motor specifications whatsoever, no battery information aside from "Comes with 2- 24volt batteries both hold an 8 hour charge for a total of 16 hours" which all we can derive from is it's likely supposed to be a "24v 16ah" pack or a "48v 16ah" pack... or it's not amp hours at all & the batteries are so pooched they won't hold a charge lol
The "You will be able to go for 16 hours" just doesn't make any sense at all unfortunately, we don't make batteries that good yet... or it's 0.03hp motor?
Again, with a base price like that it's not a bad deal at all even if you had to replace/upgrade the battery - but as we don't know the voltage/amperage/wattage of the motor or pack, we don't even know what battery type it is, yer kinda buying blind. It could be be an amazing deal for a 48v/1000w/16ah LiFePO4 bike (doubtful), or just an ok deal on a 24v/250w/16ah SLA - or something in between (most likely) *shrug*
NP at all if you're just looking for a deal, but if ya need it to do something specific like a commute or whatever there's no way to know even ballpark range & speed without that pesky volts/amps/watts/amp hours thing
edit: It looks an awful lot like this, so maybe not such a great deal after all: http://www.walmart.com/ip/21187752
"450W SLA type (no ah), rear-rack mounted, 24V, 15 mph (rider weight, input & terrain contingent), maximum range of 15-22 miles
" = 450w/24v/18a/0.6hp very likely with 2 12v 8ah SLA batteries, something like these; http://www.amazon.com/UPG-UB1280-Sea.../dp/B0009GIKNE