K30, uses an optical viewfinder.
It has 100% coverage, and not 95%,97% or lesser compared to many other DSLRs at its price level.
Horizon indicator as well as all indicators relevant to taking a photo is also there on the viewfinder.
The main advantage of an OVF is '0' lag between actual scene and viewfinder; dynamic range (ie brightness levels) (since its your own eye);
Basically WYSIWYG through the viewfinder.
EVF's merits are that it can be boost its gain in darker places (though the noise will be apparent);
Superimpose more information on the screen (whether these info add to photo taking depends on user preference);
Peaking mode on EVF is nice. With the K30, you will have to use peaking mode via rear LCD, which works too.
Scenes with large dynamic ranges (ie. brightness levels) will either clip or blow out.
Whether this causes irritation to the user depends on the individual. (I'm pretty fine with it, but some folks can't stand it)
If I were to sum up the strength of Pentax system :
1. Very well featured, good handling, good performance camera body for the price.
2. Cheap weather sealed lenses for those on a budget (18-55; 50-200; 18-135) and also good/more costly ones for those who can afford them.
3. Lenses that are typically designed to be smaller (and many small prime lens offerings that no other DSLR make has)
4. Legacy support for its lenses. (even a cheap and good manual K-mount lens from 20-30yrs back will work on a Pentax DSLR).
5. Pentax FA and DA Limited series of lenses
6. Typically DSLR bodies that are designed smaller in size
As the sample images show, sensor can be the same, but the o/p is not necessarily the same.
How each company tweaks the sensor and supporting elements like AA filter; color response; noise via hardware/software will be different.
The SLT and SLR system affects the picture o/p quality too (as the samples show)
Whatever your choice.
Good luck camera hunting.