This mod is fairly extensive and fixes or re-balances many long standing issues within various points of the game.

Each xml file is relatively well documented but a full description of the the most heavily modified files now follow:

GC2Types.XML
This file has been modded extensively. A few things to note in particular are the removal of sizemod from weapons, the overall rebalancing of all weapons and armor relating to Space vs Damage vs Cost, the hull changes (sensors are now all 1 for every hull, and tiny and small hulls get a slight speed boost, hp's for all hulls are doubled and a new hull has been added for starbases giving them a base 200 hp's). In general, there is now no huge difference between any of the beam, missile , or mass driver techs, they all give the same ratios at the same research costs. None of them are "better" than any others except when relating to what techs your opponents are using.
Sensor and Life support values have all been reduced overall as well.
Nano Ripper's have been removed since Mass Drivers overall are much better than before and Subspace Annihilator is an actual weapon now.
One final note
All sizes have been increased by a factor of 10, both as a miniaturization fix, and so that weapons and defenses can be scaled accurately

StarbaseModules.XML
Quite a few changes in this file.
New ability Starbase Range given to the influence modules from the diplomatic tech tree.
Starbase Range also given to two military modules. A few more ShipSpeed boost modules and SlowEnemies modules are given as well, available along the Engine techs. More Defensive modules available.
All modules now scale much better than originally.
Generally speaking, there are a lot more options with Starbases now, and they can hold their own much better than before. The main reasons these got such a beef up is because the ai actually uses Starbases quite well

AbilityBonuses.XML
Range as an option has been removed due to the way this mod works, refer to Raceconfig.xml for the full explanation. Luck, Creativity, and Courage have been left here as options, even though through extensive testing I've yet to figure out what *exactly* they do, but if you really want them, they are still available.
The rest of the abilities have all been given 4 options...3 small upgrades and one huge upgrade.

Anomalies.XML
Most of these have been beefed up quite a bit, so that the money bonuses aren't the only ones that are "good".
Feel free to tone them down if you feel they are TOO good as is. Personally I like them this way

PlanetImprovements.XML
A ton of changes here.
The emphasis here was to keep the ai from crippling itself (soil enhancement changes, industrial changes etc) Orbital Fleet manager is also cheap and available immediately, meaning the ai will usually have these built on their planets. Yes it's one less tile they can use for other things, but as a side bonus, their planets are quite a bit harder to kill now.

Farming improvements now start out quite small, but scale up as you get furthur into that tech tree, and the tech tree is a little longer than before. This change was made to give farm tile bonuses greater emphasis and to limit planet population size if you don't research better farms.
Other changes have been made here and there to make a little more sense.
Example: Hyperion Shipyard now gives a 5 speed boost and is avaiable earlier
There's really a ton of stuff like this here, too many to list them all, it's better if your curious to just look through the file
or look through the Galactopedia to see what changes have been made.

TechTree.XML
Most techs have been changed: their costs scaled, their ai values tweaked, etc
Several big changes to point out though.

The last two Diplomacy techs, Majesty and Total Majesty...are now "Good" only techs
The last Defensive techs are also exclusive to "good" races
The last weapons techs are now exclusive to "evil" races.
Neutral didn't get a huge boost, but with those NLC's I didn't feel they needed one.
Trade got a huge boost in the + trade bonuses category but got a nerf in # of trade routes given.
This was made to overall boost the value of trade and also to give value to taking extra trade routes as a race pick.
(Maximum hardcoded limit on trade routes is 12)

The Planetary Defense tech tree has been removed, all it did was give the player even more tech to boost soldiering
far above what the ai had. The first tech on that line has been integrated into the invasion tech tree, and tidal
disruptors has been put into the tree as well (no longer a branch).

The Starbase Fortification tree has also been removed and the modules from that tree have been moved to other techs.
Mainly the appropriate defense and weapon techs. As it stood before it was just confusing and added little to the game.

Researching up the tech victory tree gives you bonuses to your civ's research ability as well. Overall this makes
tech victory a little easier to achieve than before, but also gives a use to these techs if you have tech
victory disabled. The cost for those techs may need to be tweaked furthur, but as is are still quite expensive.

There are other minor tweaks and changes but most are pretty intuitive and given explanations within the game.

RaceConfig.XML
All races have been rebalanced and most have been boosted.
What I was aiming for was to have free bonuses that equate to about 10 customization points without using those points at all (they don't match the AbilityBonuses).
Generally this makes each civ more powerful overall, but I prefer boosting "bonus poor" races than nerfing "bonus rich" races. They should all balance out.

A Note on Range.
Range as it stands in the game is a little bit *wierd* for lack
of a better definition. Not a bug exactly I don't think, but a little un-intuitive. I've included in here a series of mods to counteract one aspect of range that irks me. Namely, that what you see in the ship designer is not the range that is displayed on the ship. To correct that, you can mod each race to have a negative range to start with which removes the "extra" range that comes from the code doubling the galaxy range bonus.
Unfortunately, since this range bonus is related to galaxy size, the range mod must be different for each galaxy size.

For example and explanation:
If you build a ship with no range modifiers on your civ and no range modules in a large galaxy, the range listed on your ship will be 0.7 sct, but once built the range will be listed on the ship as 1.4 sct, with this mod the range will now show 0.7 sct correctly after it is built, and this does affect the actual range of the ship.

For clarification:
1.0 sct (sector) = 1 large square = 15 parsecs (small squares)
Actual range of a ship from the nearest starbase or planet is calculated as:
range displayed on ship (after it has been built) listed as x.x sct
plus 0.66 sct (10 parsecs)
so a range listed as 1.0 sct will actually be able to travel as far as 25 parsecs
(15/1.0) + 10 if you follow the math.

To use this mod simply use the replace function (ctrl-H in Notepad) and replace all instances of this line

-33
(I play large galaxies)

with whatever size galaxy you normally play with

tiny
-6
small
-10
medium
-15
large
-33
huge
-50
gigantic
-65

other files that have to do with range are in TechTree.XML (removed the +range bunses from the range techs)
GC2TYPES.XML (lowered the amount of extra range with each new life support module)
and ABILITYBONUSES.XML (removed RANGE as a race pick)