Fusion by itself is hard and you barely acquire any usable energy from it... Like neutrons...
Yes it is hard. But you also get a very large amount of energy for it. Remember, the amount of matter turned to energy in a fusion reaction, is far higher than the amount of matter turned to energy in a fission reaction.
Not all the energy from a fusion reaction is released in the form of neutrons, but in Deuterium-Deuterium reactions, as well as Deuterium-Tritium reactions, you can get neutrons as the fusion product, along with other products (for example, D-D can either create Tritium or Helium-3 in addition to a neutron or proton (I think), D-T leads to a Helium-3 nucleus among other products, if I'm not mistaken.
[ame="http://en.wikipedia.org/wiki/Aneutronic_fusion"]Aneutronic fusion[/ame] is attractive for two reasons: It means you don't lose
any energy to neutrons, and it reduces your flux of ionising radiation (important when you want to reduce the radioactivity of your fusion containment vessel, as well as when shielding is at a premium and you can't afford to shield against neutron radiation- for example, on a spacecraft).
Deuterium-Helium 3 is aneutronic, but Deuterium side reactions can create neutrons. Proton-Boron fusion is also aneutronic, but there are several side reactions that create neutrons and gamma rays.
You can also harness the neutrons for energy, but I'm under the impression that this is harder to do than with charged particles (because neutrons lack a charge).
He3-He3 yields protons, and you can directly convert the energy of those protons into electricity using an electric field, due to the fact that protons are charged.
D-T is the easiest fusion reaction, so that is why fusion bombs as well as fusion power research have used it so far. I'm not sure about D-He3, but He3-He3 is harder to achieve effectively than D-T, which is unfortunate due to its advantages.
Helium 3 is also exceptionally rare on Earth, and is only found in low concentrations elsewhere...