I've upgraded these each year: 8, 16 and now 32gb. I use the 32gb in my TV for watching shows and it never has a problem with 720p HD.
It's not the fastest to transfer up or down, but just leave it to do its thing and do something else. It's not shockingly slow but class 4 (which this is) isn't the best.
Overall for the price, and depending on what you use it for, this is the best deal on the web.