Just recently put on some Subaru window deflectors. I got them mainly to allow dry ventilation when the dog is in the car or I'm camping in the vehicle.
I'm not all that happy with them. There's only about 1/2" of space between the window and deflector while it still covers or levels with the top of the window. Also, the deflector tapers narrower as toward the front, not following the shape of the top window edge. This sucks for the following reasons:
1) This leaves a pretty big gap opening, and you need to leave just a small window opening so it won't be open to rain at the front. Also, this gap creates higher frequency wind noise I find more annoying than no deflector.
2) It allows rain to blow in easier, giving you little room to crack open the window in rain.
3) You have to be careful when parking the vehicle that you cover this gap well with the window. The gap is very close to the door latch, making it pretty easy for a thief to pop it with a coat hanger if it's not closed enough.
I see the Weathertechs have a front vertical portion of the deflector, which should help with all the above issues. The Subies don't have this.
Other negatives that might be considered:
1) They are a PITA to remove. The clips that initially hold the deflectors in position are semi-permanent one-way, and very difficult to detach once clipped on. I broke both of them off the deflector thinking I could get one unclipped. It looks like the Weathertechs might be much easier to remove and reinstall, even if you might have to replace adhesive tape. I think it might be hard to remove and resell the Subies.
2) The block/distort a significant angle of view. If the scenery is pretty, you'll miss some sense of openness. Some forward corner visibility is distorted also. I find myself wanting to lower my seat height because of this, which makes entry/exit a little less comfortable.
3) I've been throw off by distorted light reflections at night. It's grabbed my attention when my peripheral vision picks it up as perhaps a moving object could be coming my direction suddenly.
