Bug-wise yes, both Photo and Designer are very very buggy.
Functionality, also yes, but not by much. Only thing I miss from Photoshop in Affinity Photo is content aware tooling. I don't remember anything I miss from Illustrator in Affinity Design and I actually think they have better features than Illustrator (admittedly haven't used Illustrator in almost a decade so maybe they've caught up).
You really can't beat Affinity's price though unless you use GIMP/Inkscape of course, but I like neither of those programs.
Functionality, also yes, but not by much. Only thing I miss from Photoshop in Affinity Photo is content aware tooling. I don't remember anything I miss from Illustrator in Affinity Design and I actually think they have better features than Illustrator (admittedly haven't used Illustrator in almost a decade so maybe they've caught up).
You really can't beat Affinity's price though unless you use GIMP/Inkscape of course, but I like neither of those programs.