[Laurent Van Winckel]

I have put together a list of things why GWA is bad and why it gets many complaints of people.

The 8 Evils of Google Web Accelerator (GWA)

1. The Google Web Accelerator is a highly invasive piece of data scraping spyware operating a technology that can create a tremendous server time (CPU) and bandwidth load on web sites it happens to hit. Web publishers are not reimbursed by Google for the resulting costs in any way.
2. GWA provides a fast proxy for site rippers.
3. GWA prefetches pages through automated processes – something Google has expressly forbidden others to do with their own site. Many of these will be pages you may not even intend to visit – Google alone decides what's supposed to be good for you. The redundant consumed bandwidth would again be ours to pay for alone without getting anything in return.
4. It does not obey the generally accepted robots.txt convention which in itself makes it spyware by definition and constitutes a high security risk for all sites hosting sensitive information.
5. GWA generates artificial impressions for paid online ads, thus defrauding advertisers of legitimate traffic. Preventing this from happening is currently within the sole responsibility of webmasters operating sites featuring such ads, in violation of which they are liable to face criminal charges of click fraud and attendant damages claims.
6. GWA gives Google the opportunity to manipulate the raw HTML code of a web site before it is received by the browser – you may not get to see what the site's publishers meant for you to find there – this again is solely at Google's discretion. And in case you're wondering: yes, they have an established track record doing this already with their new AutoLink program. This may constitute a blatant violation of copyright and trademarks.
7. GWA makes all your surfing habits 100% transparent to Google – a corporation whose top executives are known to have the strongest ties (read: security clearances) with government bodies such as the NSA, the world's largest intelligence agency. Without any accountability setup in place, nobody knows how and against whom this data is or may be used.
8. Google as a media company has an established track record of trying to steal their advertising partner agencies' high net worth clients from them. Extensive use of GWA will make them privy to any and all cookies furbished by web sites worldwide. This enables them to build an almost comprehensive database of online vendors' and buyers' behavior, sales strategies, locations, time factors, etc. Data which, when properly processed, will reveal just about everything relating to real life online commerce and its participating parties.

Finally, Google admits on their own support page that any and all passwords, e-mail addresses etc. you enter in a web form (e. g. when purchasing an item online) will be funneled via their systems.

[Source: http://webaccelerator.google.com/support.html]

This is why some sites now are banning users who use GWA. Be sure to know that.

Andylkl edit: Like what Geekerati said, USE QUOTES IF YOU'RE QUOTING!