I generally use liquid yeast and pick it up at my local homebrew shop, but it is closed now and I have been ordering everything online. I live fairly close to the MoreBeer California warehouse and my shipments don't spend much time in transit. I have ordered liquid yeast in an ice pack and had it arrive still quite cold. My last batch was a different story. I was brewing a British Brown Ale and I ordered a pack of WY1335 British Ale II, which arrived quite warm.
I made a starter with it to make sure it was viable, and the starter seemed to go OK. I never saw any krausen, but my starters often don't foam up. I did see bubbles being generated, and I finished with more yeast than I had at the start, so I thought things were fine. When I fermented the beer I never saw any krausen -- not a bit. I have never encountered this before and was concerned, but the airlock was bubbling away. After a couple of days it smelled strongly of sulfur, although that went away after a few days. It finally got to around 70% attenuation for an FG of 1.015, which was a bit high but acceptable. I eventually bottled the beer and was unimpressed with the flavor at that time, but it wasn't awful. After a week or so the beer is fully carbonated but it has basically no foam. With an aggressive pour it foams up a bit but it is thin and watery foam that falls down immediately, almost like pouring a cola. The beer doesn't taste awful, and some people even like it. I have a hard time judging because I am not a fan of that style in the first place and was brewing it for someone else.
I have heard that yeast health is important to making good foam, and I guess I just demonstrated that for my first time. Until I can once again go to the store to buy liquid yeast that I know has been kept properly refrigerated I am going to stick with powdered yeast.