It's alright. Rooms are very large, decent staff, huge pool that's fairly well kept up, complex is clean, very reasonable rates, lots of parking, nice walking distance from DLR. Never had breakfast at their restaurant, but the food for dinner was very good and really reasonable (plus 1 kid free per adult which rocks!). The restaurant is only open on weekend I think during off-season, though.
That said, I've had a few "issues" the times I've stayed there. Once the a/c would not work at all. They were very willing to let us move rooms, but it was a huge PITA to repack all our stuff and move everyone (5 at the time).
I was just there a week or so ago. Stayed there b/c most other rooms on Harbor were quite a bit more $$. I had loads of issues with the water. I was brushing my teeth the first night and all that came out of the faucet was scalding hot, even when I turned on just the cold water. That happened 2x out of the 5 days we were there. Every time I took a shower, particularly if it were in the morning, the water would go from hot to cool to hot, over and over. Very frustrating.
Sort of petty, but the ice machines never have ice. That's kind of annoying when you're really wanting a cold drink and the refrigerator hasn't made it cold enough. Not that that would keep me from staying, just sayin'.
The furnishing are very old and the beds are VERY hard, so if you have issues with sleeping on hard beds, this is not the place for you.
They charge $4 for parking, but it doesn't appear to be anywhere on their site until after you book which is annoying. Still parking is plentiful and I've never had an issue there at all finding a spot.
I've never had the water issue before, but it might have been that they were very busy (church convention) or it could have been the room (529)

. All in all it's a decent place for the money. There are other places on Harbor I like more, but I wouldn't rule out Anaheim Plaza Inn, especially if I was really on a tight budget.