This is a typical introductory offer - 4,5% for 6 months is good, but then you go down to 3% (which is still quite good compared to much of the rubbish offered in Germany!). The best way to deal with these offers is to be an interest-rate "tart" - simply move your money to the best offer every time the introductory offer ends! The only problem is that the offers are normally only for new customers, e.g. in this offer you are barred if you have been a customer of the bank with in the last 6 months.
CortalConsors is owned by
BNP Paribas (France), so you're not putting your money in any fly-by-night institution.
According to
Focus your money will be insured, even over €1.000.000 ...
...plus, I've got money with them, so I hope they don't disappear with it! (though I'm looking to move it somewhere else to get a better offer).