Stating the Solutrean hypothesis--that the first Americans came from Europe--as one of two possibilities gives it more credit than it deserves. It adds to all the Kennewick Man talk that Caucasians may have been here first. I.e. that Indians don't deserve their tribal sovereignty or land rights.
Here are some problems with this theory:
The Solutrean-Clovis Connection
A Theory for the Peopling of America
By K. Kris Hirst
Most essentially, the Solutreans of the Iberian peninsula lived 5,000 radiocarbon years earlier and 5,000 kilometers directly across the Atlantic from the Clovis hunter-gatherers.
For more on the subject, see Dissing My Solutrean Postings and Criticism of the Solutrean Hypothesis.