What good is Efika at the moment? It does not yet run AmigaOS 4 or MorphOS 1.4, or 1.5, right?
It runs MorphOS 2.0, it's just not available yet (only developing stage atm)
It is significantly slower than the Pegasos I or Pegasos II, right?
True.
Maybe someone can enlighten me about its advantages and highlights that make it a desirable platform and what uses it is good for.
It's very small. It's very cheap. You will have a factory new board, instead of used ones that are several years old (Peg & A1). It's versatile (as soon as it runs more OSes than just Linux).
True, it's also limited (no RAM to be added, only one PCI slot etc.) and slow (compared to Peg and A1 boards), but if you don't think of it as a high-end end-user machine you'll see it's worth while (imho).
What can the Efika do that my other computers can't, or what can it do better and faster than the computers that I already have?
Probably nothing. It's either the geek factor to have one, or to have a serious use for it (some embedded small form factor system running a specific task).
And like I said 2 lines above here: don't see it as the new high-end (or low-end even) Amiga or Pegasos. It's a pretty nice board to do embedded stuff, just like the SAM board. And if you are looking for a non-mainstream board to do little nifty things, it just might be the system for you :-)