Raised a bit is good. When it rains, you won't have mud flowing over it.
Exactly what is needed depends on the soil in your region and weather, too. A good pro will know what's needed.
If I were worried, I'd ask how they installed it and why. If the soil is good in your region (no expanding clays for example) and if the spot where the walkway is was already compacted, they may not have seen the need for further compaction or digging down and putting ABC or something under it.
If you want a surface treatment that's different, there are concrete businesses that do that. You've got space for a garden bed, bark mulch or rocks.
