To me it looks wonderful, especially for a first map. Jgibson's already given a lot of good suggestions, so I'll just make a focused observation. The ridges in the lakes of Istane and Nysageno look ... off to me. That's not to say that very deep lakes do not exist, they do. However, I would doubt that the level of elevation difference would be so great. They just look a tad geologically implausible to me - if they were long, narrow rift-valley type lakes, like Lake Baikal say, I'd buy it - but yours are round and pretty flat. I'd leave off the steep drop-off and possibly just paint the centres of the lakes a slightly deeper blue.