Since this question still get's asked quite frequently I thought I'd put the answer in one place so we can just link to it.
The answer is that the old HotCopper WAS broke. The infrastructure and the code that it was running was so old that geologists were starting to take an interest.
In order to keep the site running the geeks had to restart the entire system regularly. Most of you would be familiar with the regularl periods of very sluggish response from the HotCopper servers, this was part of the reason for that.
Updating the existing code wasn't an option as it relied on outdated infrastructure and there were parts of the code so old and obscure that there is no longer anyone around that knows how they work. There was a real risk that one of these components could have failed and if that happened we could be potentially have been looking at long periods of downtime whilst the techs worked out how it worked so they could fix or replace it.
So rebuilding HC was by far the best, if not, the only option.
If you remember last years attempt to transition to a new version and compare that version to this version you'll see that a great deal of effort has gone into making this site as similar as possible to the original site. There are of course some differences but the overriding philosophy has been "Add functionality but DON'T replace any function that users are used to with some whizz bang new way of doing it". You can see this with the post list concept which this time was imported from the old hotcopper. The thread list (which featured as the only view available in the first version of HC2) is available as extra functionality if you choose to use it. But you are not forced to if you like the original HotCopper way of doing things.
There are also a few features missing from the old site which will be implemented in time if there is demand from HotCopper users (e.g. the Statistics pages). And of course there are bugs and quirks to be ironed out. No matter how much beta testing you do there are some things that simply will not show up until you put a new site out into the wild due to near infinite combinations of devices, browsers and way that users do things.
Rest assured the developers are flat out right now dealing with issues as they come up (I'd guess they've had a few hours sleep between them over the weekend). And HotCopper 2 will be a work in progress for a little while yet as they respond to your feedback.
