Besides the fact that its a hella-fun sport, yes I find some value in training. Even on your own, you can draw, present, fire, mag change, etc. with some validity. I did it for a long time. Go to the range with the real gun every month at least to reinforce your grip vs. recoil, etc.
One big note: Not all airsofts are built the same. Read up on them for a while before buying one. Except for some hi-line custom makers, Marui is the only electric maker worth it. Marui, Western Arms, KSC, Marushin, Tanaka and a few others make good gas guns (pistols). And be aware of ammo, gas-type you will need (they are NOT CO2) and so on. Oh, yeah. Only Japan. No Korean, Chinese or anything else. Only Japanese gear.
One other note, for pistols you want a GBB, for Gas Blow Back. They make electrics, no dice (too slow) and non-blowbacks (not at all realistic). GBBs work like real guns except for the gas and pellets, which are both in a realistic size and weight mag.
Oh, and sometimes the gun it a tad out of spec with the real one. If you have top-quality leather, it won't always fit. This is a problem for practicing draws for some people.
There is a place called JungleToy (
http://www.jungletoy.com/). Don't buy anything thru their lame website full of Korean clones, but they franchise so there might be a bricks & mortar store in your town. Once you know a tad about it, go look at the real guns to see if you think its worth it.