Seatguru will give you the 'leg up' on your passengers by actually telling you the best seats (and worst seats) to have on an airline. Just like a stadium or ballpark you can now try to get "the best seat in the house" only on your flight.
Best site for online airline reservations!: I absolutely love this site! It's saved me several uncomfortable flights. Just enter your airline and plane type (which is almost always available from the airline's flight reservation page) and this page shows notes about every single seat on the plane. Information like which seats have extra leg room and which ones don't recline. The site is slowly becoming more overrun with extra (unneeded) functionality, but the core idea is great and I'll continue to use it.
SeatGuru Airline Seating Charts Great for Travelers: If you travel a lot like I do, or just a little and are picky about your airplane seating, visit SeatGuru to find the best seat for your needs. This site provides more in-depth information that individual airline seating charts to. For instance, where are the lavatories in case your are someone who needs to use the restroom frequently, or are one who does not want to sit next to the bathroom door opening and closing throughout your flight. It also identifies the seats with additional legroom and seats that don't fully recline. In addition, I liked how the site also offers detailed information regarding individual airlines reservations numbers, affiliated partners, and other amenities on their flights. The only drawback is the traveler has to know the specific airplane make and model to get the details since the site does not search by flight numbers. Overall, this is a great site to use for planning your next business or pleasure trip.
seatguru - Airplane information website, but who cares?: This website contains a lot of information which is good. The website is easy to navigate and it has details about all major airlines, their airplanes, and etc. Though this information is good and people would want to know these things I think each airline itself provides these necessary information for their passengers which makes me wonder who will actually use this website?
If I booked a flight with Lufthansa for example, I would look on their website for details of their seats or wifi connectivity or call the airline itself to ask something. That way I would have more assurance that the information I get is up to date.
Regarding the search feature of this website for flights; it seems to use another provider which in turn uses other providers such as expedia and skyscanner. So how many clicks before I make my booking and I am left a bit confused who I actually booked my ticket with.
I don't even need to tell you about the lack of usability features which currently are missing from the website until you go the next page of the search which is literally a different website.