Blockchain:
[ + ] Free
[ + ] If you have cellphone 2FA authentication you have to have physical access to your phone
[ - ] Servers can be hacked
[ - ] You can lost Bitcoins by phishing
[ - ] Support - I sent e-mail to Blockchain about 3 weeks ago and I still wait for answer
Trezor:
[ + ] If you want to send BTC you have to have physical access to Trezor
[ + ] Physical buttons on Trezor - they can not be hacked
[ - ] i sent a support message a week ago, still awaiting a reply
[ - ] Price: $120
[ - ] a trojan/phish can be used to make the website integration perform a man in the middle to request the seed
[ - ]cant be used easily whilst out and about, such as on smart phone
This right here is pretty accurate IMO. I don't have my trezor yet, but it should be arriving today (I hope), so I will be able to report back on the comparison of both. The convenience of being able to use blockchain.info while out and about is a major plus. Basically if you have BTC in both spots that is obviously the best.
I guess it comes down to how frequently you plan on spending BTC. If you don't plan on spending often, then Trezor is probably better. If you are frequently trading, buying, selling, sending... then maybe blockchain.info is better for you.
Obviously if you have less than $120 in BTC, then Trezor is not a smart decision.
summary:
trezor for long term "savings"
blockchain.info for SMALL "daily spend"