Pros of 802.11n - fastest maximum speed and best signal range; more resistant to signal interference from outside sources
Cons of 802.11n - standard is not yet finalized; costs more than 802.11g; the use of multiple signals may greatly interfere with nearby 802.11b/g based networks.
Sabi jan, mas malaki yung bandwidth na kaya nyang i-cater, at mas malawak ang range, at lesser ang chances na maapektuhan ng interferences like radio freqs, and the likes. Pero since it's the latest in 802.11 technology and it's still being developed and finalized, some devices are still not in line with 802.11n.
I could be wrong, please correct me. I'm not an expert.