This pistol is essentially similar to the S&W M4006, but with a SIG-style frame-mounted decocking lever in place of the more familiar slide-mounted ambidextrous decocker/safety lever. It takes the same (very cheap!) mags as the M4003/4006 and the "Value Series" M410/411; standard capacity is 11rds. The Standard Catalog
indicates that the pistol was only sold with a Novak fixed rear sight and was produced from 1991-1993.
As with other steel-frame S&W 3rd-gen centerfire pistols, the upsides of this model are low felt recoil, very good accuracy, and a generally very nice trigger, but the main downsides are its prodigious size and weight, particularly in relation to its 11+1rd capacity, which is lower than most comparable (and much lighter) polymer-frame pistols.
Value should be ~$500-$550 for a legit Excellent example that's been fired a few times but has no significant cosmetic flaws. The original box, documents, and extra mags will increase the value somewhat.
That said, this pistol is one of those guns like the single-stack Type M Beretta 92's; very few were sold, so if you think you want this one, you need to BUY NOW because it may be a while before you find another one, regardless of condition.