The highest resolution of the Optoma S341 is SVGA (800x600). That's 77% less resolution than a 1080p (1920x1080) multimedia projector, which is the most common resolution.
This projector's resolution (SVGA (800x600)) is in fact the worst resolution across all comparable spec projectors that have been around for a similar time to the S341.
A WUXGA (1920x1200) native projector resolution is the best resolution amongst similar types of projector.
There are a number of alternative data projectors that have a resolution of SVGA (800x600) currently available that you might also want to look at including the Optoma S312 (£318.68) which is cheaper.
If the resolution of this Optoma data projector is not high enough for you then you might want to look at the Optoma X340 (£311.26) (XGA (1024x768)), the Viewsonic PJD6250L (£372.00) (XGA (1024x768)), or the Acer X125H (£360.17) (XGA (1024x768)).