Anyone who is saying the internet is great "anywhere" has clearly not traveled outside of the tourist areas.
In Bangkok the internet is great. Once you leave BKK, it's hit or miss based on where you are, but you can always find a signal, it's just a matter of what speed you will have.
A lot of porn sites are blocked in Thailand so get yourself a VPN (strongvpn.com) or a proxy list. They are blocked because porn is illegal in Thailand, including downloading it, uploading it, browsing it, producing it, selling it or even building adult websites. With that said, everyone does it with little problems, just don't let the world know what you are doing there.
There are also new visa rules. A "border run" to Cambodia no longer gives you a 30 day tourist visa. The new law only grants you 15 days at the border. That means you will be given 30 days upon entry into Thailand, then 15 days each time you make a border run, until you reach a total of 90 days. Once you reach 90 days, you must then leave Thailand for 90 days before you can return. However, if you have a specialty visa (Non Imm B, Work, Student...), this can be avoided and you only have to leave once every 3 months or in some cases, only once a year.
There is a wealth of information here:
www.ThaiVisa.com Head to the forums or just search around it, all the info you will ever need is there.