I installed a Hemnes/Rattviken sink/cabinet with a Hamnskar faucet in 2017. The sink and cabinet are so far holding up pretty well, but there are a number of things I'm unhappy about:
-Ikea plumbing is highly non-standard. I had to make several hardware store runs for the initial installation, and trying to solve various issues that have cropped up over time has been.... challenging. I'm also told that none of the plumbing is up to code in my area.
-The Hamnskar faucet has a "cold start" function where, when the lever is centered only cold water comes out in order to save energy. Personally, it drove me batty. Because of this feature, the lever doesn't open evenly on both sides; you can turn it 90 degrees to the left to get full hot water, or about 30 degrees to the right.
-The Hamnskar faucet started leaking from the lever about 3 years into its life, which is incredibly disappointing for one of the nicer Ikea ones ($110). It doesn't have a replaceable cartridge, but I was able to find a new faucet from Home Depot this time for ~$90 that I've been much happier with. (If only they'd had the style I wanted back in 2017.) However, this also involved a couple of hardware store trips to undo the customization to Ikea plumbing and switch back to standard.
-Both the sink and the Hamnskar faucet came with a sink stopper. Normal replacement sink stoppers don't work with Ikea plumbing because of the low-profile drain design that allows the top drawer to work. One of the stoppers lasted about 2 years and the other is probably on its last legs. I'm hoping to beg a replacement part from Ikea the next time I go as the alternative is $40 on eBay (
https://www.ebay.com/itm/176035543554)
-At least once a year I have to adjust the Hemnes drawers because they get out of alignment. I have no idea why. This might be my children messing with them, or it could be that they just don't stay flush with the cabinet for as long as they should.
My bathroom is pretty small and Ikea had the size vanity I needed at a decent price point, but if I had to do it over again I would've looked harder at other options.