Well, it is a long tournament. I think it is better to start out slow and gain form during the championships, that is why Spain is still the big favourite, IMO.
I haven`t seen Poland yet but they seem to have a great starting 5. Of course, playing at home helps them immensely, but I don`t see them making the semi finals that would really be a huge upset. They have a good starting 5 but lack depth...
What bothers me is that there is a huge quality difference between groups. A and B are really poor whereas C and D are much more competitive...