Its much too early to determine when, or if, a demo will come out. I certainly wouldn't want to release a demo now because the game is likely to change for the better before February and we would be demoing something that is likely not going to be representative of the final product. Remember, at this stage of development of most games you are lucky if you've even seen an exclusive bit of footage of actual gameplay let alone getting to try it out yourself and then have enough time left in development to actually have an impact. I'd also say that most "betas" that are released are actually marketing tools that are released shortly before the actual release and are not actually intended to find and fix anything but minor problems.

This beta was intended for those people who want to help us test the game and who want to help shape it and we've left plenty of time to do it. We recognize that this is probably quite unattractive for a lot of people and potentially hurts our marketing efforts in the short term due to all the requests, complaints, and constant changes but we are convinced that by doing this, the final product (which is when most people get to try a game for the first time) will be incredibly stable and fun and the net gain will be much higher. I've been bitten by too many games that were released buggy and with glaring gameplay problems that any community could have told them needed to be changed. Ofcourse, that is probably your position - you don't want to get bitten in this case - and I don't blame you. However, myself and most of the community here are the type of people who like to proactively do something about not getting bitten. If I can have my say BEFORE the product is done, chances are it will turn out that I didn't waste my money.

Despite all the complaints, bugs and unfinished state of the game, the overwhelming opinion of every private email I've received and every forum (here and on many others) I've read is that Sins is very stable and fun even in its current state and things are only going to get better. Many have gone so far as to say its more stable and more fun than many finished games they've bought. As per human nature, the problems recieve the most attention after the first few days of enthusiasm but most of it is constructive criticism from people who are already enjoying the game and just want to make it great.

Given all this, the probability is that you will enjoy Sins as it is AND you will the oppurtunity to have a say in making in better. If you are still not convinced, Ironclad and the community here are doing their best to make sure the release in February is going to deliver an awesome game and if we release a demo around that time, I hope you'll give it a shot