The Unofficial Patch is a combination of the default Basic Patch which mostly fixes bugs only, and the optional Plus Patch, which is kind of a mod adding various tweaks and implementing a lot of unused content, including new quests, levels, weapons, items, characters, dialogue, graphics, models, sounds and original music! Included are also the optional Patch Extras which feature Player Mods, like shaders suites, as well as Developer Tools, like the Unofficial SDK to mod the game.
Honestly, there isn't much that can be said that can give this impressive amount of hard work enough credit. The dedication put in by all of the people working on this patch is incredible, and I truly appreciate all that is done with every single update. Wesp5 and the VTMB unofficial patch crew, thank you. Honestly, the only reason I continue to play this game is to see just what you folks put in or restore next. I have never been disappointed. Keep up the good work!
To give more of an explanation to my ramblings... Being able to take a game that on most modern rigs would shutter itself to death and making it something not only playable, but enjoyable, is an amazing feat. It would be honestly fairly difficult to play this game with just the official patches on a standard machine. For anyone who is reading this who has yet to play Vampire The Masquerade: Bloodlines without patching to any of the unofficial patch versions needs to. The official patches were great, but ultimately were a generous effort made by the Troika as their company went under. They didn't have the time or the resources to give their game the last polish they wanted to. With this unofficial patch, this game is getting that polish, and then some.
In short, download this patch. It's necessary, and it does this game the proper justice it deserves.