I use transparency on terminals since I use X. Its not to bad if i dont have it, but on a tiling wm its the only way to see whats your background image ;)
Yeah, its useless. But a bit of candy is not to bad.
I have a large screen. With a semi transparent terminal I get the impression that my brain is better able to re-scan the screen for the content I was looking for. Especially if I have a vim session with several columns.