Level1 was immensely satisfying and interesting, but the pvp challenge was .. well.. dead. By the time real life let me join others were throwing GPU based miners at the problem and traffic was constantly heavy anyway. So amazing level, the arena type thing was imho not a good idea.
PvP challange dead .. but heavy traffic? Sounds like a contradiction. I think it's a flawed deduction that the arena was a bad idea because it took more than a casual glance at the challange to be competetive. For me, level 1 was definitely the highlight of the CTF. I was one of the few who wrote a GPU miner, and the constant competition of improving my miner vs. the other active participators was extremely exciting.