So, how do you see the security of Trezor compared to the paper wallets?
Let's put aside for now a fact that it costs about 0.5 BTC to get one. That's not in my interest to discuss about, I would like to hear only about the security.
If you initialize the Trezor and write down your 24 word seed, you pretty much generated a paper wallet on a separate computer (the Trezor). If you then put the Trezor and the seed into a safe (after extracting the master public key to your computer), you should have the same security as what you can get from a paper wallet if you follow all precautions.
Of course, you don't want to spend 100 $ to have a secure paper wallet generator. The bonus of the Trezor is that you can spend from it and it is still secure. With a paper wallet your keys may be compromised as soon as you import them back into your computer.
Security related bugs can always linger somewhere in the firmware. The software bugs I have seen so far (they are all fixed in the latest firmware) required at least that you connected the device and entered the PIN, usually you also have to confirm an operation. Also they required that your computer is compromised. There is also the problem of physical theft and the PIN protection may be circumvented by hardware means. However, in that sense it is much more secure than a paper wallet, which is completely compromised by physical theft (unless you use a passphrase, which you can use for Trezor, too).
