The issue with the Moto 360 isn't the 300mAh battery. It's the usage of the 4 year old dual core OMAP 3630 processor. That processor is so old that Texas Instruments don't even make processors any more. Same processor that was in the Droid 2 way back when.
For comparison, the LG G Watch has a Quad core Snapdragon 400 processor and a 400 mAh battery, and retails for nearly $100 less.
Regarding the Hangouts update, I'm psyched. I've had a Google Voice number for years. Being able to make and receive free US and Canada calls from Hangouts is epic. Particularly since my UK carrier, Three, offers free roaming in the US as well. So I can use my normal UK sim when I'm in the US, have unlimited data, and make/receive free US calls. All for £12 a month. I feel sorry for US users paying extortionate fees to the likes of Verizon, not getting unlimited data, and getting fucked on roaming charges for using data abroad.
There's lots of things I don't like about the UK, but our mobile phone system is probably the most progressive and weighted on the side of the customer compared to any other country. I mean, you can get any new flagship phone, sim-unlocked, whether that's an iPhone 6, Galaxy Note 4, whatever, without paying any upfront cost, on the day it launches. With unlimited data. For no more than £45 a month at the absolute most. If you wait 6-8 weeks after the phone launches, it's even less. By Xmas, you'll be able to get a Note 4 or iPhone 6 here for around £30 a month with no upfront cost.