A vertical coaster sends riders "straight down", like the name implies, a vertical drop. These roller coasters are built exclusively by Bolliger & Mabillard. The drops are not actually perfectly "vertical" but are quite near, between 87-89 degrees.
It is very hard to pinpoint the "usual" features for this coaster as, at current, there are only two existing in the world: Oblivion, located at Alton Towers in Alton England, and G5, located at Janfusun Fancyworld in Taiwan. Oblivion cost twelve million pounds and the value of G5 is unknown. These coasters, built in 1998 and 2000 respectively, are not overly popular but are definitely specimens in the roller coaster world. They will more than likely be spawned in more incarnations before being retired.
Three oddities may catch the eye when watching these g-force monsters. First: the obvious vertical drop. Second: the drop terminates into a gaping hole that welcomes riders into an underground tunnel. Third: the cars. The cars equipped on vertical coasters seat eight across in two rows. Riders are restrained with standard OTSR (over the shoulder restraints).
Oblivion - 180' drop from a height of 65' above ground level. Pushes 68 mph and 4.5 g-forces.
G5 - 179' drop with a max speed of 68.3 mph and 5 g-forces.
Resources include: roller coaster database and rec.roller-coasters.