Just a couple of questions.
Would it be feasible to do the flip side of this - a 'nightmare tenants' blacklist section? - or would the legal ramifications be a bit severe? Also, what happens if some disgruntled tenant gives a property a bad review, and the landlord doesn't like it? - who's liable?
Are you planning on making money out of it at some stage? - or maybe sell to daft or something when you've built up a bit of steam.
Looks like a nicely presented site. Best of luck promoting it, before someone else gets on the scene.