Dude's covers made me buy a lot of funnybooks when I was a wee lad. Which was really the point of a cover at that time.

I"m sitting out this vote; Chan was hit or miss for me, depending on the title. His style didn't fit with a lot of conventional superheroes (I didn't care much for anything he did at DC) but I loved his Hulk. The covers he did for that character circa 1977 resonated tremendously with me at the time.

I chimed in frequently on Chan in the "40 years ago" thread, when we were in the era where he was supplying the majority of DC's covers. And my opinion was usually negative. 
If Carmine Infantino were supplying layouts, which frequently appears to be the case, he must not have often supplied any backgrounds, and Chan rarely added much of a background to anything.
If you like that look, ok, but I hated all the empty space on DC's covers of the mid-to-late 70's, and I blame that on Chan.

Chan was a good journeyman artist. He didn't shine like some of the other Filipinos, but he was reliable. I did not like his inks on some (John Buscema in Conan in particular) but like him on others (brother Sal ironicaly).
I didn't hate any thing he drew and liked some of it (I thought his work on Claw at DC was quite good).
Covers didn't do anything for me, but he wasn't "the worst"

There needs to be a "meh" option. I don't hate Chan's covers but I can't say I really like them either. His composition is often awkward, his figures stiff, and there's something about his ink line I've never warmed up to.

Cei-U!
I summon the shrug of indifference!

I voted yes. He's no George Perez, but I do think his covers are pretty good. Certainly much more of a "yes" than a "no" for me.

Elaborating on my previous comment, as best I can tell, in the mid-70's, when Chan was in charge of providing the majority of covers for DC, it appears Infantino was still providing cover designs. My assumption is that Infantino concentrated on positioning the main figures or central objects (such as the cannon on the Batman 273 cover above). A look at Infantino's Flash covers shows that he himself liked a lot of white space, so maybe Chan was faithfully executing Infantino's vision, but I'd have liked seeing the sets filled out more, and I wonder if Infantino expected Chan to do significantly more "finishing" to the cover rough designs than Chan actually did. It also appears he stuck pretty closely to Infantino's roughs, retaining clumsy figure work (such as Wonder Woman on JLA 132 above) when a better finisher would have refined things in the translation from rough to finished pencils (or to the final inks, on the frequent occasions when he inked the job). 
But Chan was working at a pretty heavy workload, often providing over half of the finished covers per month, so expediency may be the root cause of this unpleasant house look that developed on DC's covers of the 70's, with so many minimal or non existent backgrounds in monochrome. 
So I'm still coming down on the "No" side. If Chan were providing the layouts, he gets all the blame for the disappointing covers, if he was usually working from Infantino's roughs, he doesn't get the credit for compelling designs, and still gets the blame for frequently shoddy rendering and his reticence to apply appropriate finishing touches to correct anatomical distortions, awkward poses, and detailed background sets. I've just never seen a Chan cover of this era, which is where I know is work best, that I'd call anything stronger than "competently done", and plenty that I find "poorly rendered", even when the basic design was strong. 
But I've learned my lesson not to judge an artist's work from their worst, so even if I find Ernie's covers disappointing (to put it most mildly), I have enjoyed some of his interior work, which demonstrated more satisfying rendering and showed a compositional page design skill that we can (probably) safely attribute to his own talent. (There were still a lot of books published at DC around this time with uncredited layouts, usually by Joe Kubert, but I don't remember seeing evidence of that in any of Ernie's interior stories.)

And on a tangent, I can plainly see that the Batman 282 cover above is signed by Chua and Colletta, but danged if that doesn't look convincingly like a Mike Grell cover. Both Chan and Infantino were on their way out the door at DC around then, and Grell would be handling several Batman covers in the months to follow. I wonder if this was based on a Grell layout, through some chain of unknown circumstances?