I owned Asus zenfone 5 8gb since 7-8 months and yeah I can say that it is good as of now . Not Happy with the lollipop update completely but I love the phone.
Pros:
1)Good design sleek and sophisticated looks
2)Good config. for a budget phone
3)Display is vivid, almost all movies now a days I watch on my zenfone 5 with earphones in ears and blackout room, it feels lyk u r in theatre
4)Earphones are extremely good perfect level of bass, treble(This is the one which I liked the most)
5)Ram always stay free till 1300mb out of 1700 or 1800 mb
6)Availability of accessories at every possible store now
7)Can play all high end gfx games on it
Cons:
1)Battery backup is not at all good(on wifi and 3g continous max 3-4 hrs, after lollipop update draining is fast)
2) Most of the time vibrate dont work
3) too much of ram consumption by pre installed asus apps which I dnt need(you can disable it but still I dnt like it)
Overall Phone is beast for me battery backup is not a problem for me bcoz I have combined it with MI 10400mah power bank and I love the phone
Dont know abt after sales support uptil now I hv never been to service center