I'm a biased reviewer because I enjoyed the original movie from 1959. I've seen it on MST3k and unriffed as well and I truly believe it is not as bad as its reputation.
The 1959 version was marred by laughingly bad special effects where they put fake fur and very fake fangs on coon hounds and tried to pass them off as giant shrews. In fact, The Killer Shrews has been included in almost every 'so-bad-it's-good' movie list for several decades.
A great irony is the new version is also almost sunk by really, really bad computer generated killer shrews. Man, do they look lousy! They have no natural movements and the sense of proportion is WAY off. They might have been better off with coon hounds.
This is a campy, tongue-in-cheek homage done by someone who really knows the old movie. The set of the old movie is lovingly recreated complete with endless liquor bottles, comically sparse furniture and minimal set design. The movie doesn't take itself too seriously. John Schneider especially seems to be having a blast with the over-the-top dialog.
James Best, character actor for over 60 years is the real gem here. He was great in the original and he shines here too. He is surprisingly believable and steers this wacky, tacky little movie along, preventing it from getting caught up showcasing the silly, 1 dimensional background characters, most of whom, thankfully,become Bad CGI Shrew Food.
I confess I loved the original and maybe I'm not the most objective reviewer, but I really enjoyed this goofy little movie... more than I expected.
If you set your expectations correctly, you should enjoy it as well. It is a low budget, Made-for-SyFy-Channel type movie that wont win any awards for acting or screen writing but it is silly, funny, true to the original and more entertaining than I expected.