Odo's A-Pad is a very competent and getting better VSTi. Although stated as a pad synthesizer to my tastes many of the presets are a bit harsh and may fit some styles of music. This sounds bad but it's actually good because A-Pad is a easy to program synth that can make lots of things well. It's good for basses but of course it does pads well.
The timbres available with the feature set are quite useful if you know how to program traditional subtractive synths. If not, this is a nice place to start. The basic sound engine has a hard sound with a metallic quality yet with some attention to A-Pad's filters you can warm it up considerably. There's a demo song I put up from the 1.0 version at http://artistlaunch.com/elektronique called, 'Green Sky After The Storm'. It uses several instances of A-Pad, no outboard effects, just the synth.
There is a 'floaty', 'spacey' sound to A-Pad that makes any timbre style you choose appealing for ambience. While not the absolute best it is good and deserving of your time.
People are often critical of SynthEdit based VST instruments but synths like A-Pad prove you can make good sounds with it.
The interface is attractive and well thought out. If there was documentation I missed or failed to bother reading it. Although useful for different sounds A-Pad is to a degree an intentional one trick pony. As a free synth the only thing lost are a few minutes to download, set up and try it which you should consider if anything in this review sounds appealing to you.
Hands down the best analog pad synth. Nothing else to say except download it right now if you like good sounds. I could go into detail but i won't. A huge amount of quality presets, great cost (free), and some of the thickest analog pads this side of a Jupiter. Get it! version Three adds a fantastic Gui and improves the overall sound.