Having just come from completing Kingpin: Life of Crime, I have mixed feelings about the game. I purchased both Kingpin, and Redneck Rampage during the Interplay sale, and I have some positive and negative feedback about the game.
First off, I noticed in both titles (both by Xatrix) that the music cannot be turned off or having the volume lowered in any respect. That lack of functionality in a post-Quake era game is a glaring and irritating flaw - especially in a game with dialogue. How can we enjoy the wit or humor of the writing, if we can't hear it?
This is especially bad in Kingpin, where the cutscenes don't have subtitles (even if you enable them in the Options menu - all it does is subtitle the enemies in the game, so you can read them calling you names!).
My next gripe is the difficulty. I'm not a post Modern Warfare FPS player, either. I cut my teeth on the likes of Wolfenstein 3D, Doom, Duke Nukem 3D, and Heretic. But Kingpin is punishingly hard, so if you're looking for a challenge, that will be a bonus - but it didn't help my enjoyment.
The game's graphics are provided via a modified Quake II engine, and it looks good even today, though it is starting to show its age. While Half-Life might be graphically inferior, Kingpin's gameplay is nowhere near as polished or engaging. However, you see in Kingpin the stepping stones to greatness. Deus Ex would be released a year later, and it would change FPSs forever.
The NPC interaction, as well as the option to buy equipment from the Pawn-o'-Matic stores was a definite revolution in gameplay - and I noticed that the AI for the goons whom you can hire is actually quite good - better even, than some game released more recently (looking at you, Oblivion).
Still, even with the good, Kingpin falls short somewhere. By the latter third of the game, they've done away with Pawn-o'-Matic, and there are far fewer (or none, depending on how bloodthirsty you are) NPCs to hire. Kingpin falls back on the same run and gun action that Doom was (rightly) lauded for.
The story the game tells isn't particularly interesting either. It's a revenge story with a criminal bent, which serves as an excuse to throw a ton of profanity at you. Now, I use profanity on a daily basis, but this game inundates you with it. I should mention the gore - the textures on the enemies in the game show where they've been hit, and while that was probably pretty outrageous twelve years ago, it's cartoony and pointless in 2011.
In other words, don't get worked up about the gore. Compared to today (what with the Gears of War franchise), it's practically non-existent. You can blow heads and limbs off, which is something that got further delved into with Soldier of Fortune a year later, but even there it was more of a gimmick than a real gameplay enhancement.
I'm rather glad I got this game on sale, and finally got to experience this piece of FPS history - but history is where it belongs.