After of couple of months of intensive use (daily/work) it finally broke down. The left button finally got irretrievably stuck after having started to fail slightly after the first month of use and gradually got dangerously worse.
I give it 3 stars instead of 1 because it was so cheap (around 4.60 total) and it worked fine, it was ergonomically comfortable to use and overly precise (there is no cursor flashing/shaking like other mice do so, it's nice for medium/high precision and very fast work) while it lasted - pity. Will be checking other Dell models. I would recommend it as a backup emergency mouse or if you use it every once in a while, then this would be perfect and good value for money.