Is that really comfortable?

Typically the recumbent position mimics the relaxed, feet-in-the-air watching the TV position we all tend to adopt. So yes, it really is as comfortable as that.

Can I expect significant speed gains?

Fully enclosed recumbents hold all the unassisted human powered speed records, but that does not directly translate into the typcial unfaired recumbent that we see on the road. On a bicycle, aerodynamic resisistance is the 'wall' one hits when speeds start to exceed 20mph. Consequently, all else being equal (essentially rolling resisitance) one has to be riding significantly fast to notice any aerodynamic gains! Furthermore, that assumes that the recumbent is inherently more aerodynamic than an upright. Truth is that some, particularly those with a very recumbent seat and consequent very small frontal area, are, but many, simply are not better than an upright.

Can I go up hills?

The simple answer, 'it all depends on the engine' - you! The riding position relies primarily on the quads and gluteus muscle groups and does not allow utilisation of the torso and arm muscle groups as on an upright. Consequently, one can probably not generate as much power and, as there are generally no aerodynamic gains to be had at hill climbing speeds, most riders are slower up hill on a recumbent than they are on an upright.

Can I carry luggage?

Most recumbents make very good load carriers. There is lots of room behind and under the seat. For many, they make ideal touring bikes.

Why so many different designs?

An acknowledgement of the many different uses people have for their bikes. Although there are large overlaps and many make very good general purpose machines, most recumbents, actually like conventional bike, are biased to particular areas of use.

They look so low to the ground are they safe?

While most trikes and some of the low racing bikes are very low to the ground, the majority of recumbents are not as low as perceived. On many machines, the rider's head height is very much the same as a conventional bike rider in a 'tucked' position. The low bikes and trikes are a different proposition and one has to be careful to keep in the 'line of sight', either directly or in the motorist's mirrors - sometimes difficult in heavy traffic and, whilst it is possible, they are probably not the ideal choice for city centre commuting.

I'm not clear on the advantages of under and overseat steering?

Handlebar position is a very personal matter. General points to be born in mind are that overseat is more intuitive and gives a more aerodynamic profile where Underseat is very relaxing, makes getting onto the bike a bit easier and gives an 'open' position that facilitates breathing and a very relaxed, uninterrupted forward view.