First of all, it is possible to fail at a gig, and you can get quite nasty comments from your former clients.
Second, this pack encourages the use of two systems that have been in the game for a while.
The first is map view. If you look for your next clients' house and click on it, you'll pull up a panel showing all the members of that household. When you click on one, you'll see their aspiration, traits, and now, under the aspiration, likes and dislikes.
The success of your gig will depend on whether you take into account the likes and dislikes of all household members (except babies and toddlers). You can save time by doing this research before going to the house. Note: If you are playing with a fresh save, your clients might not have developed any likes or dislikes yet, so to trigger them, you'll have to inquire as to colors and decor that they like. Make special note of color and decor preferences. Activities are less useful, but they might suggest extra elements your Sim can add.
The second feature that has been around for a while is the filter system. In Build/Buy, you can find filters on the left, just above the top row of furniture. You can search for color and decor at the same time, for two or more colors, etc. Finding a green cosmolux loveseat (if such a thing exists) is a snap.
When DHD first came out, you could only cover one wall at a time. I'm happy to report that pressing "shift" will paint the entire room now. You might also see a notification that you can't change floor tiles, especially in your Sim's first gigs. This means that you can't make the room larger or smaller. You can change floor coverings the same way you paint the walls. Finally, some people have lamented that your Sim can't use furniture they've made on the wood-working table, or paintings they've done. If the furniture is in your Sim's house inventory, you can access it, by going into house inventory while in BB mode. (You can also make off with your client's old furniture if you don't want to add the money from selling it to your gig budget). To hang your Sim's paintings on your client's walls, go into live mode, take the painting out of personal inventory and hang it, and go back into BB mode.
I personally think this pack is more fun for players who are looking to add something new to an ongoing save than it is as a stand-alone. The more likes and dislikes that clients have, the more challenging it is to satisfy them. Any new save is going to start with a clean slate for everyone.