The DX881ST has a maximum resolution of XGA (1024x768). That's 23% less resolution than the most common native projector resolution of WXGA (1280x800).
An XGA (1024x768) native projector resolution is in fact the worst resolution amongst all projectors of this age and type.
Amongst comparable types of multimedia projector the best resolution is 1080p (1920x1080).
If the resolution of this multimedia projector is too low for you then you might also want to look at the Epson EB-W32 (£453.43) (WXGA (1280x800)) which also has a higher Rating.