I have one of the newer Cobra units, its ok, but I got a really good deal on it.
Valentine 1 is by far the best, it is the only one that has arrows that tell you where the radar is coming from, very nice feature, helps to weed out false signals. Also, the case design for the valentine is dated, but the internals are constantly being improved, and you can have an older V1 updated to the latest electronics for pretty cheap (that's why it still uses the same case after many years)
I have several friends that swear by their V1's (only reason I didn't get one yet is I don't have the spare cash) in fact, a buddy of mine had a situation almost exactly like the describe in the ad happen to him (double layered radar trap) he watched like 6 people get nailed all around him.