Looking at the current version, there do seem to be some kinks to work out. Haven't had a chance to play it, and I don't know when I'll have both time and company to do it, so armchair analysis for now.
Some things that would be nice to improve.
1. The Avenger first level is pretty dull. Your major class features (as far as combat is concerned) is full BAB and -2 hp for the level. The others aren't too exciting at first level, and wouldn't mind something extra. In the interest of keeping it from being a super-dip, whatever is added should be interesting at first level, but really get better later.
2. The number of talents is pretty limited (especially early on), particularly because one of the design goals is avoiding an Extra Talent feat. This is particularly true for players interested in playing the Vigilante as a 6/9 caster.
3. There should be a difference between Vigilante mode and Social mode, but it's also unpleasant to be stuck without the bulk of one's class features. (It also leads to confusing interaction- see the familiar thread.)
My solution would be to borrow from the Brawler and Shaman, giving the Vigilante the ability to temporarily use a talent they qualify for.
1. First level is not interesting enough? Have the flexible talent show up right away. Make it a standard to activate (since, as noted, these are supposed to be better than a feat- should start out slower than Brawler) and have it last for a minute. Keep the uses low and the action cost at least a standard, and it won't turn into an super-dip. Scale the uses up and the action cost down for sticking with Vigilante.
2. Talents are too limited? This allows you to try out all the talents, even if you're investing half of your permanent talents in casting or feat chains. The Avenger can act like a Brawler, picking up whatever combat feat is needed. Stalker can make use of the situational talents without dropping a talent slot on them. Warlock and Zealot can get all their casting and still try out other things, and non-casting builds get some flexibility.
3. Need to distinguish Vigilante mode and Social mode? Make using this Vigilante mode only, and make any permanent talents for both modes. Or maybe in Social mode, you access your Vigilante talents using the same pool. (Preferably with 10 min. blocks instead of 1 min. blocks, since you already have those talents.)
The main problem is permanent things (familiars, casting that needs to be prepped at the start of the day, etc.), but those are also a problem under the current system. We'll leave it as an exercise for the reader, then.