I have 4 of these drives, 2x 1TB and 2x 1.5TB, and I couldn't be happier with them
the 1.5TB HDDs came with USB3.0 adapters, and work intermittently on my Wii (works fine on my PS3 and other devices though), but if I swap in the USB2.0 adapters (that came with my 1TB HDDs) the 1.5TB drives work fine on the Wii
The USB2.0 adapters are also sold separately on the seagate website for 15 or 20 bucks. These adapters are awesome, if you have any bare 2.5" hard drives lying around (ie. without cases) you can connect it to your Wii or laptop or anything that takes a USB HDD (same applies to the USB3.0 adapters).
These drives are really sweet, but I noticed the 1.5TBs are a little slower to initialize (ie. "spin-up") that their 1TB counterparts. However, I didn't find this problematic with my forwarder channels or anything else Wii related. I mainly only notice the slower initialization times when loaded the 1.5TB drives using my laptop, but once the drive is recognize by windows the transfer rates are still really fast
Oh, a couple things worth noting. The brand new 1.5TB hard drives come preloaded with a few hundred gigs worth of movies. Also it will come with the seagate dashboard software, which u'll need to install and use to disable the sleep timer.
Another issue I've had with these drives and some WD drives is if you have 2 of the exact same drive (ie. 2x 1.5 Seagate HDDs of the same make and model) the both cannot be recognized by windows at the same (& possibly other OSs too, not sure). However, after doing some googling I learned that changing the drive signature of at least one of the drives fixes the problem. The tutorial I followed can be found
HERE.
edit: forgot to mention that obviously the HDDs would need to be formatted to FAT32 for optimal compatibility with the Wii, and they work good for everything I've thrown at them including uneek+di and things like that. And the beauty of it is that I get that same great compatibility even when connecting a bare hard drive to the Wii using the USB2.0 adapter.