I've shot the SPAS 12. I found it cumbersome and heavy for what it is. It shot fine, it looks cool. But for a functioning Semi/Pump shotgun I find the benelli superior.  (Just my opinion/experience)

A good friend of mine has one with the folding stock.  It's been a while since I've shot it, but I'll tell you what I remember.  It's an awesome looking weapon.  I think it's feature of converting from pump action to semi-auto is pretty nice, just make sure the ammo will generate enough gas to operate it in semi-auto mode.  I think the folding stock is too fragile and loose fitting.  I know Bennelli (spelling) has a model with the converting feature and it looks a lot more streamline and not as bulky as the SPAS.  I believe my friend bought the SPAS 12 for around $400 back in about '87.  Overall I thought it looked great, but was bulky.  

Too awkward and heavy.  Way to difficult swing and boy is it heavy!  NODDAH is right, go with a Benelli, M1 or M3.  8 rounds in <5 seconds. Stiff recoil, but its ok it you do it right. My M1 is light, super pointable. 18 inch tactical barrel with ghost rings.  

...fun to shoot, looks cool, heavy.
Considered to be very "evil" by the antis.
Often mentioned specifically in gun ban laws.

I prefer the fixed stock.  
Get one, you won't be disappoited.  

THEY ARE COMPLICATED, THOUGH, SO YOU MUST TRAIN, TRAIN, TRAIN.

Had 1, loved it until I had to clean it. It is a very complicated gun, to many parts for me. Went with the Bennelli M1Super90 and Remington 870.

Stay away from it, I think of it as just a movie gun.

Try not to think of it as an "either/or" situation.
I'd rather have an AR than a Daewoo, but there's nothing wrong with having both!
Get one, it's fun.

Check out this one. http://www.forthehunt.com/auction/ViewItem.asp?Item=1410995

I don't have that kind of money, so I'll just stick with my 870 Police.

Get a Benelli M1/M4 Super, and don't look back...

Jewbroni~

Only good from a collector's or "look at this cool weapon I have" perspective.  I bought one back in August of '88 ($510), but it is without question heavy, awkward and complex.  They CAN be good weapons if you REALLY take the time to train with them, but there are flat out better choices.  The $1000-1500 they cost (depending on a number of factors) would be better spent on other weapons, IMHO.

I really don't think a Benelli M3 can be beat of you want the auto/pump combo.  The M4 will be cool when it comes out, but it is NOT the same action as the M1...they use gas, as they are designed specifically with the thought of attaching optics, etc., which, as many have found out, adversely affect the recoil inertia system of the standard Benellis.  Not saying they'll be bad at all, as they went through rigorous tests with the Marines, but the M1/M3 have a good track record already.

Now if you want REAL shotgun firepower, the USAS12 with a 20-rd drum is your bad boy...but the fed says you can't get one.[:(!]

Go here for all the info you'll ever need on the SPAS: http://spas12.com/

have both spas-12(w/18 in. l.e. barrel) and benelli m1s90(w/10.5 in. barrel reg.sbs. sweet!)

spas is a nice "toy", but i love my benelli.

ergonomically the spas is primitive.
-to many buttons and levers.
-controls are counterintuitive.
-too much weight forward of your hands. (worse with 21 in. bbl.)
-must HOLD bolt release to load magazine. very awkward.
-must use heavy loads for any reliability.
-small buttplate on folding stock is punishing with magnum loads.
-cycles slowly in semi.
-only aftermarket part available is oversize bolt release button.(you will need one)
-good luck firing it one-handed with that hook.

other than that, i wouldn't part with it. looks deadly. never fails to impress my friends. the shot diverter is a nice trick too. like i said: a toy.

the benelli rocks!
-points easily
-simple controls = easy to learn drills
-feels "right" (i grew up on ar's and ak's)
-FAST! (fired an usas-12 in full-auto. i believe i can empty my benelli as fast if i needed to. saw a guy at k.c.r. reload one in a blur too.)
-plenty of upgrades available.

it did have a few shortcomings.
-very small bolt release.(i overcame this with a homemade tac release pad. gg&g wants $120 for one, sorry not this time. i did, however, spring for an extended bolt handle and safety from brownells. money well spent.)
-sensitivity to added weight. (tac light is a necessity. with the short barrel, i went with a tacam II and quick-to-see mount. very light weight and up on the side, out of the way. easily removable. sidesaddle affected reliability, so i discarded it and went with a mil-tech buttstock carrier. works fine. my theory is that the elastic has some "give" that doesn't affect the inertia of the weapon adversely.)
-requires some break-in to be reliable with light loads. (easily overcome by shooting it a lot.)

in short(not really) BUY A BENELLI if you like to shoot and want a weapon you can bet your life on.(at shotgun ranges, no less!). imho benelli has earner their price and reputation. get the spas for eye candy only. it is cool lookin'!