I've had my V-cubes for a few hours. The 5x5x5 V-cube is much tighter and requires much more force to turn than the ES. The ES can be turned with almost a feather touch; it's really easy to turn. I love the way the ES feels when it's brand new. But it definitely wears out as it gets looser. It doesn't cut corners as well as other cubes, and when you try, it makes the cube looser. So when you solve an ES, you should really solve with as light a touch as possible - never force it. (Always try to turn accurately so you're not cutting corners if possible.) If you go gently, it can last for many months before it goes bad. But it will eventually go bad. When it does, you can perform Kenneth's resurrection method, and it helps, but I've not had it help so much as to restore it to being like new.
The V-cube is hard to pass judgment on yet. It is much stiffer to turn, but feels good and solid. It reminds me of a Rubik's, but with no problem at all of twisting center pieces. It feels like it could last forever. (But apparently the prototypes didn't, so that may be illusory.) And I haven't lubed it yet; I'm waiting to see how other people lube theirs before I try. I've probably only done around 20 solves on it so far, and already it has gotten better. It feels like, with proper breaking in, this could easily become my favorite 5x5x5. But I'm sure I'd be better with an ES at the moment.
If you can cube with a light touch and don't mind the fact that the ES's "quality" lifetime is probably only a few thousand solves, the ES is probably the way to go. But if not, it might be worth going for the V-cube instead.
I think they're both nicely made puzzles. I'm glad I have both.