I have been dedicated to the P30 LEM for almost three years now. As others have noted, the action is unlike anything else that is semi-automatic. That being said, I shoot about fifty rounds per week out of my P30, and that is enough to keep my skills decent. I am nowhere near the level of many of the shooters on this forum, but I hope I am better than the vast majority who do not practice with intent.
I do supplement my P30 shooting with quite a bit of .22 LR out of a S&W 17 K-frame revolver. The DA revolver trigger is not so different than the P30 LEM. The P30 LEM trigger is lighter, and the wall is in a slightly different location, but the basic "long smooth" pull is present. I have found that, for me, practice with the .22 K-frame helps my 9x19 P30 LEM shooting. I am of the opinion that one can pretty much shoot anything well (maybe not great, but well) with dedicated, focused practice, and the P30 LEM has done nothing to dissuade me of that opinion.
As far as a holster gun, that long smooth trigger pull with a hammer I can feel makes me much more comfortable putting the P30 in a holster when compared to my last polymer gun, the Glock. There is only one trigger pull, no safeties to forget to use, and no decocking levers to find or forget. I also like that the trigger is a bit more forgiving of mistakes, something I am sure to make. The P30 reliability has been exemplary, and I like that the gun really is fully ambi in terms of controls. It is a very easy gun to learn to trust.
About my only issue with the P30 is my unwillingness to do more than detail strip. Along with that, getting parts is a bit more of a concern than Glock. In fact, no dealer within fifty miles of my home has any HK guns or parts. Internet ordering of parts and magazines has been the norm. In fact, I need to order a few more magazines to replace some that are reaching the end of their service life.
All of that being said, my wife and I have five P30 LEM pistols between us, and we have been well served by them.