The <T> shortcut alone makes Vimium a must, it makes switching between tabs so much easier. The only drawbacks of the extension I’ve found are having to adjust settings for the odd websites that have shortcuts and certain elements not working well with Vimium “clicks” (like the Lemmy sort order dropdown list!).
As another happy Fairphone user, I’d caution against getting one though if you don’t see the hefty price tag as also being a way of subsidizing right to repair and fair trade. The long warranty period and support duration, the repairability, and the SD card slot might not be enough positives to offset it being bulky, heavy, the camera being terrible, security updates coming with 1-2 months of delay, the specs being generally under what you’d find around its price range and you going 300 USD over budget.
Personally, I’d only ever owned a low-end smartphone that was 4 years past its end of support before getting the Fairphone, so I’ve been very happy with it, but I can see the drawbacks mattering more to other people.