I have 2 500GB Seagate Momentus XTs, as well as about 10 SSDs. The XTs have been great, especially for the price I paid of $59. I did try to use one as the main boot drive in my laptop - it much better that my previous hard drive, but didn't give me the same "SSD" experience that I hoped for. So it is not as good as an SSD, but it still is a very good drive. I placed as the OS drive in my son's desktop, and it works great, and for his usage it's almost SSD-like. My other one is used as a storage drive, mainly for Steam games and videos, and it works great for that as well.
For the price I paid, I'm extremely happy with them, but they are a lot more expensive now.