From a security perspective, you are giving full access to your machine (above OS level) to a crew of hobbyist developers, who may unwittingly introduce security holes into your OS, or even worse, have a bad actor in the group who is trying to hack old macs. All of this is pretty unlikely (you aren't very likely to score big money from someone running an 11 year old laptop, there are better hacking targets out there).
From a usability perspective - OCLP sometimes breaks with Mac OS updates, particularly if you run the latest OS. Not all OS features work, although most of them do. You have to go through a process of re-installing patches after every OS update (which is now automated!). You can avoid most of this by running the previous OS version (i.e. Sonoma, or, even better, Ventura instead of Sequoia) as Apple doesn't change things in older OSs too often.
For my usage - this is fine. My main machine that I use for secure dev/banking is a modern M1 machine. My daughter uses a 2015 MacBook Pro 13" rescued from the junk pile at work, and my son uses my 2012 MacBook Pro 15". Both of these machines run Ventura nearly flawlessly, running the latest apple apps and versions of Office for homework.
From the current state of OCLP, it looks like they may not be too great on Sequoia (Photos doesn't currently work, which would be a showstopper), but they should still be down for two more years of Apple security updates even if the OCLP team don't work around this, which they probably will.
