I think that Jovi's 'sound' is more than just the talk-box. The tone, melodies and harmonies are all characteristic features and instantly recognisable traits of a Bon Jovi song so for the talk-box to be considered a 'signature sound' is IMO a little superficial.

I do think they over-use it but at least it is always kept rather subtle on newer songs. How critics can claim that they are trying to write LOAP part 30 just because they use it in any given song shows just how little they actually know about music. It is an effect at the end of the day - just like the wah pedal and countless others are. It should be used to colour a sound (like in Everyday) or song (as it does on LOAP and IML) but shouldn't be used perhaps as much as it is.

The way I see it is, if you're gonna use it, USE IT! Like they have on 'We Got It Goin' On' which features a real talk-box solo. It has to warrant it's place in a track so give it some balls and not some half-arsed, subtle flavouring in a song so that you can only hear it if you really listen for it!