I have a 20 month gap between my two and I have found it very hard work at times.
I must admit, it was not the newborn days that I found the hardest. Martha was a dream of a baby and Tom was pre the "terrible 2s." I am a real believer in routine and worked hard to establish a workable routine for us all early on. Tom became much more demanding quite literally the week he turned two, and some days our routine simply went out the window, this is something that I struggled with at the start, I have become a bit more relaxed now!
I continued to send Tom to his childminder 1-2 days a week (even for a few hours per day just) and I found this helped massively- I got a little break and he got lots of stimulation and some pre-Martha "normality." I also sent Martha to my mams house to bring Tom swimming once a week, to ensure he didn't feel completely left out.
I did/ do feel an incredible sense of guilt that Martha has had no where near the attention that Tom received when he was a baby. She is not attended to every time she squeaks, she isn't rocked to sleep, she has blue bibs on and she isn't bathed every night, but is happy, healthy and has a brother who loves her and I need to keep reminding myself of that!
Yes, having two babies is tough. There are times I have thought 'what have I done?!' There are times that I've felt completely out of my depth, but on the whole it has been great and I honestly wouldn't change anything.