I'd agree and disagree with this.
We went in September last year for 4 days. I'd read a lot about the big queues at places like the Colosseum beforehand so I knew what to expect. We got there early in the morning, about 8:30, and there was no queue outside. People still tried to sell us queue-jump tickets, claiming there were massive queues inside, but we decided to wait in the normal queue. Once we got inside the ticket office, there was literally 10 people in front of us - but a lot more people waiting in the 'queue-jump' queue!
Having said that, I do wish I'd paid for a guided tour rather than just walking around ourselves. There's so much to see that i'm sure we must have missed at least 50% of it.
It might be a bit busier when you go in summer. If you can, it might be worth going to the Colosseum the day before you plan on going in and checking what the queue is like, how fast it moves and if it's worth paying for a tour/queue-jump.
Here's a couple of tips:
-Your entry ticket covers Colosseum, Roman Forum and Palatine Hill. That means you can buy your ticket at a ticket office at any of these places and use it to get into the others - look for the smallest queues.
-Take a bottle of water with you when visiting these places. There's drinking fountains around but it's much better if you have a bottle you can refill at them.
-The open-top tour busses are quite a good way to travel around. They go to all the places you'll want to visit and you get a day ticket and can get on and off as much as you want.
I didn't find it particularly expensive to eat out. In fact, my favourite place was
this one. More of a takeaway with a few tables and you get your pasta on a paper plate with plastic forks but it's made fresh in front of you and tastes amazing! It was something like 4 euros for a plate of pasta.