Before I bought this mouse I read a lot of reviews and obviously had concerns about the battery life - I bought it regardless. I then read on the logitech forums that it is not the battery life that is bad, it is the battery life indicator on the mouse that is wrong, if you google something like logitech g700 battery indicator wrong, you will find the thread I am referring to. In the thread somebody plotted a graph etc. and the problem is that the indicator seems to be calibrated to normal alkaline batteries. Normal batteries start at 1.5v and as they deplete the voltage drops, the type of battery in the g700 (sanyo eneloop) starts at 1.2 and doesn't drop much until it is nearly depleted, this makes it appear like the battery is nearly dead pretty early on, but it has loads more charge left.
So, I put it to the test and didn't charge the mouse from opening the box until it died, it lasted 2 and a half days, most of this was on one green indicator light and I have been playing games all day pretty much so the mouse was in maximum gaming mode for a lot of the time. Bearing in mind that the battery could have been charged a long time ago so may have lost charge from the factory/warehouse to my house. If your motherboard still powers the usb ports when it is turned off then the battery isn't a problem, it will last all day then just charge it at night. This type of battery doesn't have to be depleted before you charge it, however they do have a limit on how many times they can be charged.
So onto the mouse itself, my best mouse, out of my previous mouses, was a cyber snipa silencer. I will be comparing to this mouse mainly. One thing I noticed straight away was the feel of the mouse, the outer shell is entirely made of plastic, with a textured, rougher feel on the sides. I do not really like this, I prefer rubber on the sides, not just for the feel and better grip, but also they tend to have grooves cut into them which means your hands don't get as sweaty. A thing I just really noticed as my hand gets sweaty with this mouse.
Another thing is your ring and pinky finger will scrape across your gaming surface/mouse mat, my previous mouse had 2 channels for your fingers to rest on and underneath was the mouse feet so your fingers never touched your gaming surface/mouse mat. This is obviously something I will get used to but it is my main dislike with this mouse. The scroll-wheel feels a little wobbly, maybes due to the ratchet/free wheel system - not a major problem but annoying again. These few things just make it feel a tad cheap to me, especially comparing it to a mouse which costs half the price.
The software is very easy to use, the pre-set commands are great, although I don't really use many of them it is great to have copy and paste as 2 of the four side buttons. I did have a problem in that I couldn't get it to auto-switch profiles for various games, this could be that all the games I play use a launcher, steam etc. and it is more-than-likely a user error. Instead I simply press the g11 button which swaps my profile from maximum gaming to productivity (I don't bother with general gaming), this is my preferred method of profile switching anyway, mainly due to laziness setting up auto-switch and ease as you just press a button.
In game the mouse feels great, the lack of a cord is obviously great, the mouse has no lag that any human could notice, the buttons are well located and very easy to press, the most difficult probably being the g8 button (the bottom one of the 3 little ones on the top), the 4 buttons on the side are easy to distinguish and easy to press (hardest thing is just getting used to there being 4). The LMB and RMB are very satisfying to click, something I never thought I would notice on a mouse, but they feel very mechanical and give a good click, the buttons are sturdy and have no wobble (says something about my old mouse).
If your battery did die during a game and you have to use the charging cable you will not be happy, it is horrible, so very thick, not flexible, heavy, just so awful especially from going from beautiful wireless to the worst wired. If you charge it overnight you will be fine everyday. If your motherboard does not power the usb ports you can just plug it into an iphone charger, it works but obviously do it own risk etc. but really it will be fine. Or you could just buy a battery charger and batteries and you will be good to go.
I would give it a 4 but the things wrong with it are just things I am not used to having, after using my previous mouse for over 2 years daily, bar the slightly wobbly scroll wheel.
After using this mouse for a month I can say: The battery lasts about 3 days before it has been on critical too long and I should charge it; I got the auto-switch profiles to work (user-error); I bought a rechargeable battery from ebay for £1.30, if a battery runs out during a game, change it fast and then recharge the dead one over night.
This is a 5* mouse.