I picked up a sample of Gel de la Mer a couple months ago to try as they were out of the Creme. Even the sample jars are quite nice, like minature versions of the full size.
The gel has a light ocean-ish fragrance similar to that of the Radiant Infusion. I'm guessing most of La Mer's stuff probably has the same fragrance. The La Mer Tint has a much stronger scent I find...which I'll post a review on separately.
The gel is light and refreshing, similar to other gel-type moisturizers. In terms of feel, it has a much lighter feel than Clinique's Moisture Surge Gel (which feels thicker). Gel de La Mer also sinks in faster than the Clinique one. When comparing the two, I noticed Clinique's would leave a slightly sticky residue behind, while La Mer leaves a smooth feeling behind.
Some visual comparisons - they look pretty similar in terms of texture. Added Nars Aqua Gel Hydrator in there because it was lying around...
Moisturizing properties - it doesn't moisturize my combination skin enough, which gets dry and flakey in winter. It would be perfect for summer I think, although I may still need some extra moisturizer on drier areas like my cheeks. Very similar to Clinique's Moisture Surge in this area (see my review if you missed it).
Other benefits - I couldn't tell if the gel actually improved my skin because the sample jar was too small. It'd probably take a month to tell if there was any benefits. Unfortunately that amount you see gone was used up in two weeks, maybe because I have drier skin.
Nice lightweight texture, great for normal to oily skins. However for what it costs, I'd say go for Clinique's Moisture Surge gel instead, they both ended up being for about the same, but Clinique is cheaper and fragrance-free. I still prefer Lancome's Aqua Fusion gel cream over those two as it moisturizes my combination-dry skin better.