Read: http://www.ricoh-imaging.co.jp/english/products/whypentax/index.html
But as the top "Pentax hatred site" on Earth, I have to write five of the most updated reasons for why not Pentax now so as to make the balance, namely as follows! ;-p
1. Pentax is not Pentax anymore, its name disappeared from web and on lens (the name plate and marking was removed)! And, there is no SMC anymore! >:-o Now comes the HD, yes, it is 720p only, not even 1080p! ;->
2. There is no Full Frame Pentax which never comes true even after twelve years since the old MR52 prototype in K-mount was first created! Non, there is never any concrete plan of a FF that is official!
3. There is no REAL new Pentax DSLR body nor REAL new lenses for more than two years now! For instance, the K-50 is identical to the old K-30 of the last year. The K-500 and K-50 "are" also essentially the same camera body! K-5II is just a K-5 of 2010 with no significant improvements. Yes, they changed the LCD monitor, add one and only one f/2.8 AF sensor. But so what? Could the development of two years only give those?! As for the lenses, there are only repackaged ones with new colours. Yes, colour variations, their strongest point for long!
4. Pentax colour rendition is no more Pentax by now and indeed, worse than the current Canons', IMHO!
5. There are more problems with Pentax and actually Ricoh for their camera business and strategy (if any). But since I have to be concise and confine points to five, the last point is that the Ricoh named Pentax will probably soon to be doomed and has no future. So, should you buy and invest into such a dying and eventually dead system? Don't blame me on my this point but which is 100% valid. What Ricoh has shown us for their plan(s) and give us faith on the future of the brand?? Name changing!?