okay, the dictionary isn't perfect, there IS some limitation on words beginning with re- & un-. however you can make a lot of words ending in -er & -ing & -ed since these are common letters.
however the dictionary is probably better than many other word games. the downside is you get used to certain words in bookworm, then can't use these same words i other games.
a good strategy is to give yourself "protection" by having a horizontal row of bonus tiles at the bottom, this will slow down your burning tiles. you can keep a game going a long time.