The price was one thing that I found very attractive. I like the fact that it comes with a lot of things that people would add on anyways(expansion, venturi bolt, beaver tail). After playing all summer with the marker I was very impressed with its accuracy and consistancy. I also found that it was easy to strip down and clean or maintain.
Good feel in the gun and it even looks alright. I suppose another plus would be part availability. Since the Intruder is a Spyder clone, there is a huge amount of parts out there, both upgrade stuff and repair stuff. Plus there are many people who know how to deal with them.
The first tournament I entered it in after a few months of rec ball was a disaster. My velocity jumped up to 350 and wouldn't come down. Several people tried to look at it, but without luck. Changing a bunch of seals seemed to have helped the problem, along with a new spring, but I still have some pretty inconsistant velocity. I have also found that I need to cock the gun half a dozen times when gassing it up and often if the trigger is pulled without a ball for some sort of back-pressure the marker won't recock all the way.
Overall, I like the gun. Hopefully the bugs will get worked out soon. I find that for a gun for someone interested in getting into some tourney play or maybe even a first gun, this is an excellent marker. As for comparability to other markers in its class, I would say it stacks up very well for its price range and compared to other Spyder type markers.