Summary: I originally went with the '300 mbps' model (with two antenna outputs); the two silly antennae on the back got me about 30 mbps. In order to have improved that situation, I would have to attach not one, but two large, cabled antennae, which would have looked plain ridiculous and added little value to that presented by this combo. The 150 mbps card with 5 dbi antenna is the pair to buy.
Pros: First, never expect that a tiny antenna on the back of your PC will be sufficient; they never are. You must pair this device with TL-ANT2405C if you expect to get anything over 20 mbps (with this antenna, I have nearly 70 mbps [150 mbps stated]). At about $20 for the pair, the combination is pretty tough to beat.
Cons: None, assuming you don't expect the silly included antenna to do anything.
Summary: Before I used this PCI adapter, I used a USB WiFi adapter. I thought that by actually buying a PCI adapter, my signal would be better so I could get rid of the USB adapter. What happens is, well, the USB adapter was faster and had a better signal (again, where I'm in the house) than the PCI card. I'm a bit disappointed, but it's still awesome.
Pros: Works great most of the time.
Cons: Where I am in the house (somewhat close to the router without interferences), I only get 50% of the signal. It sometimes gets a bit up to shortly get back to 50%. It happened once that it went even more down. Even though the signal gets low, the internet connection stays on, it doesn't pause it.