Sorry, but I have to disagree. I have never liked the look of a blazer with heavy raw denim (heavy, as in the color and cut are heavy), and I think that uniqlo generally calls for something more minimal. If that were an old chore jacket, sure, but the boots and jeans are too clunky for the jacket. I'd also have to advise against the black crew- a black T- neck would be fine, but the crewneck-under-blazer is something I associate - not positively - with the IT crowd.
On the plus side, the blazer looks like it fits well - and so do the jeans. Maybe try something a little sleeker on the bottom, like a pair of black 511s, even (I'm assuming blazer is black - can't really tell); and combined with a sleeker shoe I think you'll look great. As it is, though, I think that the bottom half is just a bit too heavy. I have a fairly specific look in mind when I wear jeans and a blazer, though, so feel free to disagree.