I find them useful in summarizing State of the Art to get me going in a new topic, but then again so is Wikipedia. A useful side angle, if you using LaTeX, you can cut-and-paste references into ChatGPT and can turn them into Bibtex format with >80% success. For a PHD study though starting from textbooks, papers etc. it will be better, but can augment successfully, like any tool use it for what is best.