Yes, I guess it was the logical move. He did not feel finished as a top level racer, and he found the chance to continue competing at the top in America. Good of him to go for it. Here's hoping he enjoys a successful and safe year.
The last pre-season testing got underway today;
2012 Pre-Season Testing, Day 1, Test 2, Circuit de Catalunya
Pos Driver Team Time Laps
1. Grosjean Lotus 1m23.252s 73
2. Button McLaren 1m23.510s +0.258 64
3. Perez Sauber 1m23.820s +0.568 118
4. Webber Red Bull 1m23.830s +0.578 102
5. Rosberg Mercedes 1m23.992s +0.740 128
6. Vergne Toro Rosso 1m24.216s +0.964 113
7. Di Resta Force India 1m24.305s +1.053 98
8. Massa Ferrari 1m24.318s +1.066 105
9. Petrov Caterham 1m24.876s +1.624 123
10. Maldonado Williams 1m25.587s +2.335 58
For a comparison in times:
2011 Pole Position lap:
Mark Webber, 1m20.981s
2011 Fastest in-race lap:
Lewis Hamilton, 1m26.727s
In other words, they're slower this year. Even if they're not going for absolute top speed, they should not be three seconds off what the cars are capable of. In race trim, you'll be slower due to tire wear, extra weight due to gas as well as not pushing as hard for one single lap. You'd rather be consistent over 60 laps than mix fast laps with slow ones.
Of course, these times do not mean much. They're not testing for outright speed. A Sauber beating a Red Bull, a Ferrari down in eighth place, it means nothing. However, when reading through the trends, it's easy to spot who're doing better than others.
For example; Red Bull, McLaren and Lotus seem to have the fastest cars in outright speed right now. In addition, Red Bull and McLaren (and perhaps Mercedes) seems to have decent long-distance pace. Other teams doing surprisingly well in pre-season testing include Sauber, Force India and also to a degree Toro Rosso. On the contrary, Ferrari are struggling as is Caterham.