False.
AIM v4.8 final (or even 5.1.*) with DeadAIM v3.0 is free of ads and bulky toolbars. It works as a plug in so it consumes very little memory and works with the aim.exe (adds ~1MB of memory to the aim.exe process). DeadAIM also adds an easy to use message logger, transparency, cloning, etc.
Older versions of AIM are not compatible with newer options, such as IM Images, mobile IM, file transfer/sharing, and so on.
And AIM does NOT have any spyware (no matter what version).
Best of all, if you are up to the challange, you can use ResHack and remove any and all options you don't want to see.