The Sega Saturn's demise can be traced at least partially to the difficulty of programming the system. While it had two SH-2 CPUs, writing code to utilize both of them was non-trivial at best and exasperating at worst. Developers described the system as a pile of chips on a board; You could do anything with it, but the burden of figuring out how was your own. As a result, most systems make poor use of the second CPU. By comparison the Playstation has a single MIPS R3000 CPU (fabbed by LSI Logic.) While the unit clearly has less CPU power (though the R3000 is a more fully-developed core than the SH-2, which doesn't even have a floating point unit) the playstation is easier to write game software for. The Playstation also had sound hardware which could be played essentially like a MIDI device with loadable voices, a feature much-desired and appreciated by game developers at the time.
Another technical barrier to acceptance came from the lack of a transparency unit in the Saturn's graphics system. Any transparency effects had to be carried out in software, which was a common use of the second CPU. Unfortunately, transparency effects done in this way were still inferior to those carried out by the Sony Playstation (PSX) at the time. The Saturn will do 2D hardware transparency in the same style as a GIF image, which is to say some color (or mask) will be replaced with whatever it is displayed over. You can use this to do fast screen-door transparency in software, an effect seen (For example) on the Saturn port of Daytona USA. (This title is ideal for pointing out the Saturn's use and behavior because it was included with nearly all Saturn systems.)
Sega put good graphics hardware in the successor system, Dreamcast, but overcorrected on the lack of development tools by choosing Windows CE (WinCE) as the primary development platform. Developers did not see CE as much of a choice, and primarily avoided it. Many WinCE games were bad (and unstable) ports of Windows games which flopped badly, all of which led to the eventual demise of Sega as a console game manufacturer.
The sega saturn was special (especially for its time) in terms of capabilities and capacities. It has nearly twice the ram of the playstation, internal memory with a battery backup (Using the standard CR2032 lithium cell), an expansion slot which could be fitted with a Video CD player, and the ability to play CD+G discs (for karaoke.) The system supported two controller multitaps for a maximum of twelve controllers supported simultaneously, though the only title I am aware of which uses more than four is Saturn Bomberman which uses ten, either on two of the six-port standard multitaps or a single custom multitap intended to look like Bomberman's head. The unit had both a double-speed (300kBps) CD-ROM drive suitable for playing VideoCD, but also a cartridge slot in the top of the unit which was used for cheat code carts (like the game shark and action replay), save game memory (both directly accessed and memory you could use when not in a game to back up your save files in the internal memory), and as a 4MB RAM expansion for a couple of games. We have seen only one console system with a memory expansion since, the Nintendo 64. It in fact also used a 4MB RAM expansion, though it uses RDRAM rather than ordinary DRAM. In addition, one game (Marvel vs. Capcom 2?) used the slot as a ROM expansion, to hold the game sprites for faster access than getting them from the CD.
In addition, the original controller used was much like the genesis fighter controller (six buttons) plus two digital triggers. The saturn later got a "3D Control Pad" which had six buttons, two analog triggers, a gamepad, and an analog "joystick" which looked like a ball with a bite taken out of the top into which you placed your thumb. Interestingly enough when Sega made the Dreamcast they deleted two buttons from the layout but the controller is otherwise similar.
The Saturn still has a strong cult following in the US even though it did very poorly here due to the paucity of games, leading to the eventual death of the platform (See above.) Some of the games with the highest hype-to-players ratio are on this platform, including Virtual On (complete with optional twin stick controller), Saturn Bomberman (possibly the culmination of the series, and it certainly supports the most players), Dragon Force which is a fantastic and deep fantasy RPG, Bust-A-Move/Puzzle Bobble 2, 2X and 3, possibly the best examples of that series, and many more. It was also the home to many excellent true-to-arcade ports of fighting games including the Street Fighter series (On Street Fighter 2 Collection), Marvel vs. Capcom, and others. Until very recently, even in 2000 or perhaps 2001, Japanese developers were still making new titles for the Saturn.
The Saturn can be modded much like other consoles, removing copy protection features. Unlike other systems which require only one chip, generally a small and simple microcontroller, Saturn protection mods are actually a small PC Board which plugs into a socket on the motherboard and has a socket on it to take the flexible circuit which it displaces. The games can then be copied as if they were any other CD. Saturn games generally consist of one ISO9660 "Yellow Book" track, and one or more CDDA "Red Book" tracks. Unfortunately for those who would play copied games on the Saturn, few types of recordable CD are readable by the Saturn's antiquated laser unit; The older blue CDs generally work, but the newer green ones do not.