I have a 630W, and during the initial installation we faced several issues. First, there was a cyan ink leak in the printhead tower; the warranty service replaced all the ink tubes in that section.
Another problem was frequent print interruptions due to printhead failures without any apparent reason. The white ink was not recirculating between the IMB and the cartridge, and we also experienced the freezing issue that others have mentioned here.
HP eventually decided to replace the entire unit. The new one doesn’t have as many issues, but it still stopped twice reporting a carriage jam, even though there was no real obstruction. We also had to replace three OP printheads that were marked as damaged.
HP support told us to use the printer without the vinyl side support plates, claiming that could be the cause of the repeated printhead failures.
Honestly, I feel like lately HP users have become the beta testers for their plotters.