I tried it out successfully for the first time the other day (had 1 false start some months ago). This is after 10 ish years of system wide installs or venvs. I didn't find it fast at all. Every time I went to run the script it spent multiple seconds checking dependencies. Then one time it updated one, which luckily didn't break anything but I did get concerned. I'm sure there're some flags I didn't know to use but uvx was not great. On the other hand, it did seem to install the packages faster than pip.