It's pretty much impossible to be 100% safe, but for a convenient wallet that you can use for everyday spending, it's safe.  If you want to know about how TREZOR in particular is trying to deal with security concerns, read their page about it here.

I can personally vouch for the quality of TREZOR's interface and their support as well.  It's all very user friendly, there are regular updates and the support is helpful if you have any problems.
When you buy a hardware wallet they ask you to write down a "seed", which is a collection of words which you should keep in multiple locations.  If your hardware is damaged or if you need to have access to the funds in multiple places for whatever reason, you can import the seed into a new hardware wallet or into any other wallet which is compatible with their type of seed.