prescott is cheaper than northy's @ the same clock speed and should oc better if you get the proper board for it (everyone's mileage with oc'ing will vary)...
the longer pipelines and the larger NUMBER of pipelines denotes this processor was designed solely for speed... also keep in mind the processor has 1mb l2 cache which should help in some situations...
clock for clock it does less work and is therefore slower than a northwood (both for socket478 for reference sake) BUT the extra l2 cache should help and the sse3 instruction set and tweaked HT should also help once apps take advantage of the differences...
heat is a problem with prescott's but if you get a decent cooler you should be fine... not my top recommendation (I suggest a64 for mid-high end users) but not a total disaster... privately I am disappointed in it

because so much PR was expended to show it was so uber (reminds me of nvidia with the nv30)... but not a total loss @ the price