There are only 2 brands making projector headlights. 99% of members have the version shown in this thread. The other ones aren't even worth mentioning due to the inferior quality of the...."projectors". As for these, from what I've read....

Pros
MUCH better light output vs. stock headlight housings.
Halos are a nice touch, but if you don't care for them, they don't have to be wired/turned on.

Cons
Cut-off's too low (adjusting them till the light output is high enough tends to leave a big gap between the headlights and body of the car).
Some have bouncing issues.
Some have leaking/condensation issues.
Using HID bulbs will void the warranty.

If you're still interested in them, you can find them for under $200 shipped now on eBay and Newegg.