I shoot as much 40 as I do 45 and 9mm now. It is a very versatile round, especially if you reload. You can load up very accurate soft recoiling target rounds. You can also buy very powerful defensive rounds in any flavor you want.
If you are a speed devotee, then use a 135gr going 1420fps. If you are a heavy-for-caliber person, use a 200 grain going 1100fps. If you are somewhere in between, the 180gr at 1120fps or a 165gr at 1150fps might be the ticket. If you don't like the snappy recoil, use the old FBI load which was a 180gr going 950fps, or the old "police lite" load which was a 165gr going 980fps.
You can make major in the shooting sports with it much easier than 9mm, and during the recent ammo hoarding, I saw more 40 available than 9mm or 45.
The 9mm sized 40 caliber guns fit my hands a little better than the 45's too.
A lot of the people who don't like the 40 are the shooters who absolutely HAVE to have the fastest most powerful ammo they can buy for it, and then complain that it is too snappy. It really isn't snappy at all if you buy ammo in the velocity range that it was originally marketed with.