I am of the opinion that Whizzard is one of the most underrated Runner Identities going.
His basic stats are standard, 45/15 and no link. However, I have encountered several people who say that his runner ability isn't good because some decks do not run trashables. To me, this is akin to people saying plascrete is bad because not all decks run Scorched Earth. This is true, but misleading. Plascrete is common because whilst it isn't universally useful, when it is useable it will save your life.
Whizzard's ability might not always be of immediate use, but when it is, it will frequently win games for you.
I do not mean this as hyperbole. There are extremely few decks that do not run any assets or upgrades (CI being the only one that leaps to mind) and several strong archetypes (RP, NEH, etc.) that run several very powerful examples. Sundew, MHC, Jackson, Adonis... all become free to trash. PAD costs one. SanSan and Eve cost two. The runner cannot afford to leave them undefended when it is so easy for you to trash them. (well, except Jackson in certain circumstances).
This can give you a significant advantage in the economy game that is at the heart of netrunner.
The other, less obvious advantage is that his abilities do not tie him to a particular deck build. Noise, for example, is always going to be virus bombing; Ken will focus on events; Sillhouette on exploiting expose... Whizzard can run almost any deck archetype you can find the cards for, as most have no effect in any way (positive or negative) upon his ability. In that regard he is somewhat like Kate or Reina, in that the ability will be almost as helpful in any deck you make. (Although Kate's and Reina's will trigger in every game).