Speaking as a Samsung advocate...
Huawei phones from the P10 onwards (especially this latest P20 series) are off the charts. They're good. Very good.
They manufacture their own Kirin processors, and these are generally as good as, if not better, than the latest Snapdragon and Exynos processors that Qualcomm and Samsung, respectively, manufacture.
Build quality is good, but not amazing. Samsung and Apple still have the edge when it comes to durability and the premium feel of materials used, but not by much.
The cameras (especially from the P20 onwards) are the best on the market. As an S9+ user, I thought I had the best camera on a smartphone until the P20 Pro came out and absolutely blitzed it with its 5x optical zoom. Low-light photography still isn't as good as the Samsung, however, and the OIS is still quite shaky when it comes to any sort of video.
The screen is LCD, which means it drains on the battery more than the AMOLED screens that Samsung (and now Apple with the iPhone X) are using. So to counteract this, Huawei pack their phones with larger batteries which ensures that the battery life is as good as the aforementioned.
UI experience is different for an Android phone. I would say it's more like an iPhone than an Android due to the layout - it's just all one home screen, no app drawer or anything like that. Although, due to the open nature of Android, there are launchers that you can download to give it any feel you'd like - classic android, a custom theme, anything.
Huawei's fast charge is quicker than both Samsung and Apple's. It can charge 50% in about 32 minutes, which is great for such high capacity batteries. I believe it's actually the quickest on the market right now, though I may be wrong.
Umm, not much more to say really. The model I'd avoid would definitely be the P Smart if you are going to go with Huawei. It's just a phone they made look expensive, but has really poor specs. The dual-camera isn't even that great.