Ha! I know it! SFII is way better thatn SFIV... if it has a nekkid shower scene!
I think I should post the SFIV Unlocker.

Already found links to that while searching for some guides. Don't want.
I really don't think Microsoft would be bold enough to charge another $20 for the DLC on the PC when there are hundreds of new skins out there by now and considering how the PC version had virtually nothing new except for the 6 month delay but well - they are. The size of the DLC is of course ~20 KBs because EVERYTHING is already provided in the default installation, just some variables need to be set to 1 instead of 0, which is what the trainer does. -.-
Ye... I was quite astonished reading the price in the marketplace... I mean... WTF? o_O
As to SFIV being "overloaded". You might not know this but most of the stuff that is in SFIV was in SF2 too - you probably just weren't able to play it at that level back then. Watch some pros playing HD Remix and be amazed.

I think overall the only new things are: Focus Attacks (though SFIII had universal overheads and parries instead), Ultra Combos, dashes and EX Moves (though EX Moves and dasheing have been around for a long time, just not in SF2).
Let's phrase it this way: I never played it somehow pr0 (like I never play anything pr0), but I had no serious problems to beat the CPU on higher levels. But in SFIV the fucking Abel even annoys me on easy with the fucking throw system. -_-'
You don't need to really "know" too much about the game - stuff like techs, counters, reversal etc. all come out naturally if you just play the game correctly.
... so pressing keys randomly?
And combos, which of course were in SF2 as well, you simply need to learn and train over and over again - no reading involved - just finding out which attacks can be canceled by going through the trials...
I really miss a "show" function in the trials where the game just shows you how the stuff you have to do looks like. Otherwise it simply sucks if ya trying move X and doing some basics not the right way.