Well, it's called a 'recumbent' bicycle. The word recumbent refers to the seated position; some American enthusiasts have also taken to calling them 'bents'. They usually have two wheels although some have three. They are most often powered by pedalling with your legs, but some bents are hand powered, some are both hand and foot powered.
Are they comfortable?
They are very comfortable. Recumbents seats are larger and you actually sit in the seat. You aren't perched on top of a narrow saddle which can tend to cause numbness and chafing. The handlebars are either above the seat at shoulder level, or below the seat at a position where your arms hang down naturally. This combination creates a comfortable ride making long distance riding free from neck strain, saddle sores, and wrist pain.
Are they difficult to ride?
No. It may take you a little time to get used to the feel and handling of the bike. There are variations in handling just as there are in uprights- some are fast, twitchy racing models and others are smooth, stable touring models. Be forewarned though, recumbents use different muscles, so even if you are a very fit upright rider, you will experience difficulty climbing hills until you develop the new muscle groups.
Do they "do" hills?
Yes, they do "do" hills. Some people think that because you can't stand on the pedals, that you can't ride up hills. Recumbents do tend to be slower going up hills, but as long as you keep pedalling the bike keeps moving. Depending on how steep a hill you're climbing, you may want a low granny gear (and a good set of lungs), which will enable you to spin your way to the top. Usually you can keep up with some of the upright riders, and if any time was lost climbing, you will make up for it on the downhills and flat ground.
Are they faster?
The fast ones are much faster. In the IHPVA sanctioned events, all the land speed records are held by recumbent or semi-recumbent designs. The real question you are asking is, will you be faster on a recumbent? The answer is,"maybe". There are so many factors involved; how long you've been riding, how long you've trained on the recumbent, style and weight of the bike, topography - hilly, mountainous, flat. Since the biggest factor limiting speed is aerodynamic drag, if you want to go really fast, use a recumbent with a well-designed fairing or a full body. In this case, the answer is YES, they are faster.
Are recumbents hard to see?
Since recumbents are relatively uncommon, they are always noticed. The effect is similar to riding down the street with no clothes on, you will be the most conspicuous thing around! If you ride in a position where you are obscured by other traffic you will of course be invisible, although this would be true whatever vehicle you were in, and you should adjust your riding style accordingly.
How do you steer it?
Generally, recumbents have either 'above seat steering' (ASS), or 'under seat steering' (USS). On the above seat steering models, the handlebars are located at about shoulder height giving them the "chopper" look. On the under seat steering bikes, they are located just beneath the seat. If you are sitting on a chair right now, let your hands hang loosely at your side; this is where your handlebars would be. Above seat steering looks more conventional and is therefore sometimes favoured by beginners; but USS recumbents are really no more difficult to control since recumbents, like conventional bikes, are steered by movements of your body weight.
Have recumbents been around a while or are they a recent invention?
Recumbents have been around since the mid 1800's with the MacmillanVelocipede and the Challand Recumbent. In 1933 Charles Mochet built a supine recumbent named the "Velocar". Between the years of 1933 and 1938 pro racer Francois Faure, while riding the Velocar, set several speed records for both the mile and kilometre. In Paris on July 7, 1933, Francis Faure broke the 20 year-old hour record of 44.247 km. by going 45.055 km. Unfortunately Faure's hour record created a controversy amongst the Union Cycliste Internationale (U.C.I.), the governing body for bicycle races. The controversy was based on whether the Velocar was a bicycle and whether the time records were legal. In February 1934, the U.C.I. decided against Faure's record and banned all recumbents and aerodynamic devices from racing. That is the reason why recumbents have not gained popularity in the racing scene, and why they have not been mass produced by bike manufacturers. For over a century since the introduction of the Rover Safety Cycle, built in England in 1884, the design of the basic diamond frame bicycle has hardly changed.
What are the different styles of recumbents?
The most noticeable difference between the different styles is the length of the bike. There are long wheelbase (lwb), short wheelbase (swb), and compact long wheel base bikes (clwb). A long wheelbase bike (LWB) is 65" - 71". Their ride is quite smooth, comfortable, fast and stable but due to their length, low speed manoeuvrability can be a bit tricky on busy streets or on narrow paths. Examples: Ryan, Linear, Peer Gynt, Tour Easy.
A short wheelbase bike (SWB) is 33" - 45". Their front wheel is underneath or a little ahead of the riders knees, with the crankset mounted on a boom. They have quick handling, are easy to manoeuvre, and they are more compact, making it easier to transport and stow than a lwb. Examples: Street Machine, Challenge Hurricane.
A compact long wheelbase bike (CLWB) is 46" - 64". These bikes are the easiest bikes to learn on. They are responsive, very stable, and with a higher seat- they are more visible, making great commuting bikes. Examples: HP Velotechnik Spirit
I'm still slow! How long does it take before I'm up to speed?
Since it takes time to develop new leg muscles it will depend on how often and the amount of time you spend on your trusty steed. For me, it took about two weeks commuting on it 20 miles a day. For others it may take up to a month or it may take less than two weeks. It all depends on your physical fitness and the how hard you choose to ride. Whatever happens... don't give up !