Of course you'll be able to choose between the two. It's not that the yearly plan replaces the monthly, just another option. So if you like monthly, you stay at monthly.
There are of course pros and cons to yearly plans. It can give bunq an income boost if people pay for a year in advance, but in the long run it can cost them money, because most bunqers will stay for longer than a year anyway.
I also think that bunq is worth the money. Not because of all cool features, but because of the filosofie. I really want them to succeed. But like I said, it can help them too. People will commit for a year and are maybe less likely to leave within that year. bunq can also get a short term income boost. I'll leave the math up to bunq ;)