Most will agree that up to some lvl this is one of the best damage weapon in the game. The question is at what lvl to stop using the wurmy. Or at what lvl will the more frequent aplication of the primary hand str bonus out damage the higher damage rate of the wurmy. Based on DPS (damage per sec) at lvl 58 there are 19 damage/delay combo that will out damage the wrumy that did not out damage it at lvl 25. Most of these weapons are hard to get, and a number of them are nodrop. The most popular of these is the Lam. Again based on DPS the Lam will do slightly more damage than the wurmy at lvl 49. This differance will become noticable at lvl 51.
The Effect of Missing
Some believe that since the damage is so high with the Wurmy that a miss will have a larger inpact than it would with a lower damage fast weapon. The fact is, missing has no more effect one way or the other. Yes the wurm will miss for more (if you will) however the fast weapon will miss more often. A certain percentage of your swings will be misses, and thus the more you swing (with a fast weapon) the more you will miss. Same thing with the crits, dubble attacks and so on. The crits you get with the wurm will be larger but you will get more crits with a Lam. The only exception to this is repote (sp). When you block you opoints hit and score a hit. This will favor the Wurmy, since the frequcncy of this attack if a function of the delay of your opoint.
Effect of Haste
For the most part haste dose not change the DPS ratio between weapons. The exception is that there is a minimun delay of 10. This being the case it is possible to obtain enough haste that the Lam can get no faster and part of the haste effect is wasted, under these conditions the Wurmy can once again out damage the Lam.
In short the wurmy is a weapon usable to the highest lvls, however if you have the means and or the time after lvl 50 you might want to upgrade to a Lam. This is of course dependent on how much haste you can count on day in and day out.