To Hell & Back Again is both a fun satisfying solo adventure as well as being a tremendous introduction to the Descent Into Avernus campaign.
The adventure is split into three distinct acts each with its own flavour that none-the-less tie together to form a coherent story. My personal favourite was the second act wherein the player gets to interact with an Infernal Warmachine and go on a journey with Lulu the Holyphant. The adventure also takes the character through three levels and will give them some additional perks/flaws/quirks that will continue to have an impact on them after the fact if they are continuing their adventures in Avernus.
Overall I found the adventure to be very narratively complete while also having enough dpeth mechanically to still feel like a legitimate 'gaming' experience.
[5 of 5 Stars!]