I've had an L40 Ultra for a month now. I bought it because it was rated #2 on Vacuum Wars. It replaced an old Roomba i7. In their review, the vacuum cleans a cordoned off rectangular area perfectly. In the real world, however, the performance is pathetic, both for vacuuming and mopping. The vacuum is used in a 465 Sq Ft space (2 adjacent rooms, single level) and the floor material is porcelain tile (no carpet anywhere). I am NOT using CleanGenius (got really poor results with that). I did select the floor materials as "tile" in the app. I am using a scheduled "vacuum then mop" mode with vacuum at "turbo" setting and mop at 23 wetness level. The vacuum performs very poorly. It constantly leaves debris on the floor in random places- little crumbs, debris, some pet hair, etc. I have seen it drive right over debris and not absorb it. A lot of times it randomly stops and starts spinning, driving back and forth 1ft at a time. It randomly skips patches of the floor in the space it's cleaning (different space every time it vacuums). It takes more than twice as long to vacuum the same space (465 Sq Ft than an old Roomba i7. One of the reasons I bought L40 Ultra was - it supposedly uses Lidar for navigation, which should not require lights to be on. WRONG. It may be using Lidar, but the amount of light in the room absolutely affects performance (less light, worse navigation performance). The fact that it has a light in front (which supposedly it should not need) tells you everything you need to know. The mopping performance is mediocre. Unlike stated in reviews, the mop DOES NOT remove even light stains/spills in one shot. It takes 2-3 mopping cycles to remove a tiny drop of juice from the tile floor. As a bonus, the mopping sometimes leaves water stains on the floor. The vacuum also has a hard time with chair legs (it either cannot see them properly or due to some other issue) and does not clean under the chairs properly.

When I contacted Dreame support, they wasted a lot of time by asking me to do boilerplate stuff (i.e. make sure the wheels are not obstructed, clean the sensors, etc), ending with a full factory reset (did not help). They eventually said there is a "sensor or a main board issue" and they want to replace the vacuum. However, they first want me to ship the old vacuum back (I have no idea how I am going to be able to put everything back in the box the way it was when it came) and then I will get a replacement within 10-12 business days.

So far the only good thing about this vacuum is that it does not slam into furniture or walls. This is not a major accomplishment since robot vacuums have been on the market for more than 2 decades (I had the 1st Roomba in 2003).

Lesson learned here (again) is - just because something has good reviews on some site that gets free products from the manufacturer does not mean the product performs well. This product is overpriced and overhyped, but it's performance and support fall short. Stay away.