The Halls of Runehammer is a very enjoyable and well written adventure. Though it is designed for 5th edition (and works extremely well, I might add), it has a feel to it that would definitely stand up to any of the original D&D or AD&D modules. It is very well written and laid out, and it has all sorts of maps and random encounter tables for the DM to make use of. If an area is of any importance, you can be assured there is a map for it.
There are a couple of typos that I found, but they are very minor (like a "the" got left out or deleted for example). I honestly think I found them only because I was really looking. The artwork varies a bit in quality, but it all still works really well to capture the atmosphere that the creators were aiming for. Overall, the quality is very good, and I am definitely impressed with the adventure.
Back to the good stuff (and there's a lot)
Without spoiling anything, the adventure has a great story behind it while remaining action packed as well. As a matter of fact, the adventure pretty much starts with all the action that low level characters can handle. Yes, the adventure is very challenging and potentially deadly, but resourceful players will most likely find their characters coming out on top (barring bad luck of the dice, of course).
The adventure itself is around 75 pages, with the rest being new monsters, NPCs and magic items. There is definitely enough material to provide several sessions of game play. Some of the more random locations are briefly detailed to allow individual DMs to expand certain encounters by adding their own ideas. These are optional locations that lie off the beaten track (and may not be found by players), but will add a nice touch to the adventure as a whole.
Yes, while the adventure is definitely action packed, there are puzzles to be solved and plenty of opportunity for roleplaying with various NPCs as well. It will definitely test the mettle of 2nd to 4th level characters, but will reward them appropriately as well. It makes for a great 5E adventure (really a great adventure for any edition), and it is a perfect opportunity for characters to really begin the trek towards becoming heroes. I would highly recommend giving this adventure a shot!