For a first try, Noctua has done a very good job. This compound has features that are in line with most other thermal materials being offered and goes a step further by ensuring their customer base that it is perfectly acceptable with phase change cooling. While this may not be a big deal to many, it is looking to be a more readily acceptable method of cooling in the near future. If compressor-based cooling can come down to an affordable price point, it will take off, no question about it. To know you have a product that is future proof is a good thing, and it doesn't hurt that it performs well under normal condition also.
As far as price is concerned, MSRP is set at $8.95USD and can be found online for about $8.50 with a little effort. While not the cheapest compound on the market, it is still cheaper than AS5 and performs better too.