People ask me what having twins was like and sometimes I can't recall specifics it was so much of a blur for us. DH and I were both working off hours and it was so stressful. We were exahusted most of the time. It was a great experience but I don't think I'd want to relive those early years.
We have a large family room that we completely child proofed and cushioned, lol. We added a playhouse and small slide and eventually toys and books and such, and they stayed pretty busy there. I do remember days, though, where it was only 9am and I'd already pulled them off the ledge about a hundred times and I wondered where I'd get the strength to go on for the rest of the day. (I found it somewhere but I milked those midday naps until they were almost 4!) We also spent a lot of time walking outside and at playgrounds, etc.
As pp's mentioned, things got better as they got older. We spent a lot of time together as a family (and still do). Even though ours are a boy and a girl, they've always gotten along well and enjoy spending time together. Sure, we've had to break up some knock-down-drag-outs at times, but overall they're very caring about one another which is great. There are a lot of benefits to having two the same age.
Ours just turned 13. I've spent a lot of time reflecting where the years went. I always tried to remind myself not to "wish it away" especially when things got crazy - based on what others told me about how fast it goes by (which it really does). I was also diagnosed with breast cancer when they were just 5yo which gave me a whole new perspective on the time I had with them and how I wanted to make each and every minute I was given with them count, as there were a few years I wasn't sure I'd have the opportunity to be there for them or see them grow up, etc.

They have clearly been the most important job I've ever had - and the most rewarding. It's hard to think that in just a few years, they'll be off to college, which blows my mind because it seems like I just had them.
So as hectic as it gets, and as tired as you get, know that they're a blessing and there will be a time you miss these days (even if it's a wee bit).