Update 2: Rebalanced against the new science recipes described in FFF-159.
Update 3: Red science can be made by hand again, oversight on my part, sorry.

For both new players and veterans! Better Science aims to give smoother game progression by adjusting science and technology. Many players feel that the jump from green Science 2 to blue Science 3 is too great, especially considering how effortless it is to make purple Science 4. Since technology (and thus the production of Science) controls game progression and flow as well as the player's abilities, the game experience is improved by making them more closely follow a "traditional" progression curve. Peaceful players will be happy to hear that with Better Science, the Rocket silo can now be achieved without any fighting (or even military technology, sans Rocketry)!

Each of these features can be tweaked or disabled in config.lua:
- Improves Science pack recipes to follow a traditional progression curve. Silky-smooth transition through oil. Purple science is harder than just dropping Artifacts in a blender.
- Alien science (now "Science 4") needs a little petroleum-derived Transformer oil. This increases late-game fun by requiring you to snake some new pipes into your factory. :)
- End-game research is more involved, requiring one of four specialized new types of Advanced science. For example, the last few levels of Robot follower count will need Advanced robotics science. Show off your end-game logistics skills by feeding your Labs with an total of eight types of Science packs!
- Overall materials cost of all research is kept similar to vanilla. This is configurable with a multiplier. It's even possible to disable all other features to just use this.

Existing saves will migrate when loaded, but I would recommend starting a new game for the full experience. Much care has been taken for wide, automatic compatibility with other mods - Better Science will update their technology costs too. Mods that follow naming convention and extend vanilla technology, in particular, will require appropriate Advanced science (eg., the Military 5 mod will now need Advanced military science).

Forum thread.
Here is my reference chart about the costs of science packs.