It is but
1) Its free
2) Its footprint is much smaller than PowerISO
When you install it, all you'll ever really see of it is some little icon on your toolbar which you can launch and mount ISOs. It also comes with some emulation for security measures used on modern PC games (this is if your going to go all out pirating shit).
I've never had issues with it at all. Its a great app and is one of the first things I install when I first setup my PC.
I was able to install, and the game started and everything, but when I tried to install the mod, it didn't work.
You need to install the Mod files in the root of the Planescape folder. The path should look like...
C:\Program Files\Black Isle\Planescape - Torment
You want to install it there. Then you'll get the CMD prompt and have it install at whatever res you want (x being the longer axis). It installed fine for me.