Level 1 "Oh Yeah More Lemmings": an easy introduction. It was straightforward to get the silver talisman. I have not attempted the others.
Level 2 "Season Round":  a long but not too difficult level. Getting the bronze talisman needed some careful thought.
Level 3 "Adventure of Pharoahs": another straightforward level, with a very generous time allowance.
Level 4 "Exit towards End": more of a challenge, with some tricky sequences needed to get the talismans.
Level 5"Lemmings in firework factory": it took me a while to work out how to use Platformers in different places to keep the crowd safe.
Level 6 "Dockyard": a nice puzzle. It's possible to save 49, compared to the required 47.
Level 7 "A lot at once lemmings": I struggled more with this than any other level in this rank. Use the Bomber and the Basher in the obvious locations, or swap them around? If a Builder is needed to rescue fallers, how to get this facing towards the exit, so the Builder does not head off and drown? Could using the Bomber in a 3rd location solve this problem? Eventually I realised that making full and proper use of the Hang-Glider is the key – though the solution needs precise timing in the early part of the level. Once the correct strategy is found, getting the talisman is easy.
Level 8 "Bottom of the well": a surprisingly easy level, needing just over a quarter of the time allowance.    
Level 9 "Re Energize your lemmings": another entertaining puzzle, with one of the two lemmings helping to rescue the other. Time allowance not so overly generous here, but still ample.
Level 10 "Going Up Lemmings": completely different from most levels in this rank, in that the required strategy is obvious but execution has to be pixel-perfect and frame-perfect. I beat the time limit by a tiny 0.06 seconds.
Level 11 "Crystals Cliff": another breather level. Here I looked for a strategy not using Bombers, so all 50 lemmings could be saved.
Level 12 "Think Fast Disarmer": not too difficult but still an enjoyable puzzle. 
Level 13 "Winter Rush": one of the more difficult levels in this rank. Do you get 1 lemming to the end, reverse it and bash back all the way? Or try to get past all the obstacles with the small number of skills provided? Or go for a hybrid approach? I reckon only one of these 3 options is viable. 
Level 14 "Twins Parkour": another entertaining 2-lemming level. One lemming has to wait while the terrain is prepared, but the time limit is not massively tight.
Level 15 "Donuts Paradise": I suspect there several alternative solutions, though mine has only 1 Builder to spare.   
Level 16 "Create a Paths": this took me a while to solve, until I realised that using the first Cloner in the right place would remove the problem I was facing towards the end of the level.
Level 17 "Gem Cathedral": here the talisman solution was completely different from my first effort – and with so many Builders to spare, I used some to speed up the later lemmings. Using the Digger in the right place was vital.
Level 18 "Caution Walk Over Bridge": a quick but entertaining challenge. It took me a few minutes to see where to use the Shimmier, because originally I wrongly thought it would be needed elsewhere.
Level 19 "Clone Wisely": one of the easiest levels in this rank, if you pay attention to the title. 
Level 20 "Miners and some dynamites": lots of Miners and Builders needed here. There must be quicker solutions than mine, but again I wanted to minimise the use of Bombers.