To answer the OP question, if this would be a step up for you, and something you are interested in, you should look into it. While many on here are whiners, in my opinion, this has been a great company to work for. Regardless of where you choose to work, do your job well but remember that only you care about what happens to you, so look out for number one while doing your job. You don't owe them anymore than just your best while it is best for you, and if you see a better opportunity, take it. No such thing as a long term relationship anymore in this environment.
To answer the other question regarding good people being let go, who the hell knows. As companies have switched from clear business rules to this new way of using outside companies to tell them what to do, there seems to be a lot of collateral damage. This unfortunately is not specific only to Amgen. I was downsized out of a position with another company because I lived in the wrong zip code...literally one block away from the "right one". I was a two time award winner, and lost my postion to "middle of the pack Jack". (Our compensation was not too drastically different, either) My thoughts are with those who were cut while in their prime, so to speak. Only consolation is those are the ones that are usually snatched up by another company rather quickly, and often times at a better compensation. WIshing them all good luck in the hunt for something bigger and better.